Conditioned response-contingent delays of the unconditioned stimulus in human aversive conditioning. Four groups of subjects were given either 0. 100, 500, or 1,000 msec delays of the unconditioned stimulus (UCS) contingent upon the occurrence of a conditioned response (CR) and were given a UCS 515 msec after conditioned stimulus (CS) onset when a CR did not occur. A fifth group received standard classical conditioning trials with an interstimulus interval of 515 msec. Overall performance decreased as CR-contingent UCS delay increased, with the classical conditioning group approximating the performance of the group receiving the 100-msec delay. The data were analyzed with the two-phase model of conditioning and the following results were obtained: The duration of Phase 1 of the model increased with contingent delay; operator limits associated with CR trials or with combined CR-CR (CR absent) trials decreased as a function of delay; and operator limits associated exclusively with CR trials were unaffected by the delay. Subjects receiving a contingent delay of 0 msec gave the shortest latency responses and exhibited reliable latency decreases across trials, suggesting an attempt to "beat" the UCS. The results were interpreted as contrary to what would be expected from low-of-effect theories which postulate that reinforcement results from a CR-UCS interaction, although they could be subsumed under a drive or an associative strength theory in which the aversive, or CR-supportive, strength of the UCS is assumed to be negatively correlated with contingent UCS delay.


Storage and retrieval properties of dual codes for pictures and words in recognition memory. Storage and retrieval properties of pictures and words were studied within a recognition memory paradigm. Storage was manipulated by instructing subjects either to image or to verbalize to both picture and word stimuli during the study sequence. Retrieval was manipulated by representing a proportion of the old picture and word items in their opposite form during the recognition test (i.e., some old pictures were tested with their corresponding words and vice versa). Recognition performance for pictures was identical under the two instructional conditions, whereas recognition performance for words was markedly superior under the imagery instruction condition. It was suggested that subjects may engage in dual coding of simple pictures naturally, regardless of instructions, whereas dual coding of words may occur only under imagery instructions. The form of the test item had no effect on recognition performance for either type of stimulus and under either instructional condition. However, change of form of the test item markedly reduced item-by-item correlations between the two instructional conditions. It is tentatively proposed that retrieval is required in recognition, but that the effect of a form change is simply to make the retrieval process less consistent, not less efficient.


The von Restorff effect and induced amnesia: production by manipulation of sound intensity. When an outstanding item appears in an otherwise homogeneous list of items, the outstanding item is better remembered (the von Restorff effect), and items before and after it may be more poorly remembered (induced amnesia) than corresponding items in a control list. In the present experiments the outstanding item was a word presented as a loud shout among other words presented at normal conversational levels. In two experiments, large retrograde- and anterograde-induced amnesiae effects were demonstrated using a free-recall and a recognition task. In both experiments half of the subjects were told what to expect and were instructed to devise a strategy to eliminate induced amnesia. These instructions failed to eliminate the amnesiac effect. A third experiment was designed to demonstrate an empirical similarity between induced and clinical amnesia. In clinical retrograde (but not anterograde) amnesia, "lost" memories are sometimes recovered with time. Filled delays of 0, 30, or 120 sec interpolated between list presentation and recall demonstrated that induced retrograde amnesia disappeared at the longest delay but induced anterograde amnesia was unchanged. A fourth experiment eliminated some alternate interpretations of the effect.


Immediate and delayed recognition of sequentially presented random shapes. Two experiments tested whether short-term memory accounts for the recency effect observed with rapid sequential presentation of nonverbal stimuli. Four random shapes were presented sequentially (with no interstimulus interval) on each trial at rates of 150 msec, 250 msec, 500 msec, and 1,000 msec per stimulus. Subsequent recognition varied positively with exposure duration, ranging from 57% at 150 msec to 77% at 1,000 msec. Two serial position effects were observed: a slight decrease in recognition accuracy for the first stimulus in each sequence and a large increase in recognition for the last stimulus in each sequence. The recency effect was not altered by an intervening 30-sec delay, an intervening 30-sec copying task, or an intervening 30-sec copying and counting task. Since neither visual nor verbal distractors altered recognition accuracy, it was suggested that all shapes were processed directly into long-term memory storage. It also was hypothesized that long-term storage of a nonverbal stimulus requires identification of a distinctive feature of the stimulus and that this process may continue for a brief period after actual stimulus offset.


Enduring visual memory despite forced verbal rehearsal. The ability to decide rapidly that two visual stimuli are nominally the same when they are also visually the same (the Posner effect) was examined for stimuli of increasing visual complexity (Experiment 1) and when a greater variety of visual differences between the two stimuli was employed (Experiment 2). When the two stimuli each consisted of a pair of letters or when to single-letter stimuli sometimes differed in both case and style, the Posner effect occurred even though subjects made overt verbal rehearsals of the first stimulus. The results suggest that losses of the Posner effect found under simpler circumstances are not attributable to a switch from visual to exclusively verbal coding.


Cell patterns and cell movements during early development of an annual fish, Nothobranchius neumanni. During epiboly stages the cells (called deep blastomeres) which will form the definitive embryo disperse over the surface of the yolk sphere, only later aggregating and developing an embryonic axis. Five different statistical tests were used to study the pattern formed by the deep blastomeres during epiboly and early dispersed stages. The two most reliable tests, based on the distance from each deep blastomere within a selected area to its nearest neighboring cell, indicate that the distribution pattern changes from regular during epiboly stages to random during dispersed stages 1 and 2. Careful observation and time-lapse microphotography revealed some aspects of how the cells set up the regular pattern. The deep blastomeres exhibit a variety of cell extensions, with which they often contact one another. When two deep blastomeres make contact during epiboly stages, they soon break the contact and move apart; they overlap one another only rarely. Deep blastomeres are frequently located at, and are even elongated along, borders of the overlying flat cells (enveloping layer cells). These two mechanisms, one similar to contact inhibition of cell movement, the other to contact guidance, may contribute to the rather regular spacing of the deep blastomeres as well as to their arrangement in rows during epiboly stages.


The dicyemid Mesozoa as an integrated system for morphogenetic studies. I. Description, isolation and maintenance. The morphological simplicity of the dicyemid Mesozoa is such as to allow mapping of enery individual cell during the development of the organisms. Individual cells are of a size amenable to micromanipulation and a number of potential morphogenetic makers is readily apparent. The possibility of raising the animals in vitro and obtaining developmental mutants makes these organisms excellent candidates for use as an integrated system to correlate cytodifferentiation and morphogenesis with genetic control. An axenic, nearly defined, medium in which the misozoans can be kept for over three months has been developed. Methods for isolating and maintaining the organisms are described.


A preliminary investigation into the roles played by the rectal gland and kidneys in the osmoregulation of the striped dogfish Poroderma africanum. Presented here are the results of a preliminary investigation into ionic and osmotic regulation by the kidneys and rectal gland of the striped dogfish, Poroderma africanum. Fish with ligated rectal glands showed an increase in blood concentration of sodium and chloride within a short time period, reaching a maximum after four days. The blood concentration of the two ions then decreased over the following ten days. Control animals showed relatively unchanged blood-sodium and chloride levels, over the entire 14-day period. After salt loading, both control animals and those with ligated rectal glands showed initial rise in blood sodium and chloride levels, but these returned towards initial values within seven hours of injection. Comparison of the two groups indicates that the rectal gland may control blood-chloride levels more so than -sodium, although its action as a salt regulator does not seem very pronounced in either case. Urine and rectal gland fluid, were collected as a compound fluid, from normal fish, and the estimated cloacal salt loss is discussed.  Urine from normal fish was also collected separately and was analysed for its contribution to salt loss. Results are discussed and compared with previous relevant findings.


Acetylcholinesterase in singly and multiply innervated muscles of normal and dystrophic chickens. II. Effects of denervation. Neural regulation of mature normal fast twitch muscle of the chicken suppresses high activity, extrajunctional localization, and isozyme forms of acetylcholinesterase (AChE) characteristic of embryonic, denervated and dystrophic muscle. Normal adult slow tonic muscle ofthe chicken retains intermediate levels of activity and embryonic isozyme forms but not extrajunctional activity; it is not affected by muscular dystrophy. The hypothesis that neural regulation of the AChE system is lacking in slow tonic muscle and thus not affected by dystrophy was tested by denervating the fast twitch posterior latissimus dorsi and slow tonic anterior latissimus dorsi muscles of normal and dystrophic chickens. Extrajunctional AChE activity and embryonic isozyme forms increased, then declined, in both muscles. The results suggest that ocntrol of AChE is qualitatively similar in slow tonic and fast twitch muscle of the chicken.


The differential effects of estrogen and progesterone on the uterus of the ovariectomized golden hamster. The effects of estrogen and progesterone on incorporation of 3H-thymidine by the uterus of the ovariectomized hamster are reported. In the ovariectomized hamster progesterone alone did not induce incorporation of 3H-thymidine. Estrogen alone caused significant incorporation of 3H-thymidine, predominantly in the luminal epithelium wheras a prior or subsequent treatment with progesterone activated DNA synthesis in the stroma and muscualris. These results indicate the role of estrogen in priming the uterus of the hamster for the subsequent action of progesterone.


Tooth replacement in the upper jaw of the rainbow trout (Salmo gairdneri). The present paper describes the pattern of tooth replacement in the upper jaw of two size ranges of rainbow trout (standard lengths 12-15 cm and 20-23 cm) as determined from wax impressions of the dentitions taken twice weekly on anaesthetised fish. There was considerable variation in the nature of replacement waves (lines constructed on dental charts linking eruption times of alternate teeth) between fish for both the premaxillary/maxillary and vomerine/palatine rows. The wave patterns obtained showed the same consistency of form for any one animal which is to be expected when consecutive generations show constant or proportionately changing life spans. Data relating to the life span of the teeth is given. The results are compared with those derived for the lower jaw and the significance of wave form discussed.


A reexamination of cleavage patterns in eutherian mammalian eggs: rotation of blastomere pairs during second cleavage in the rabbit. The pattern of cleavage was examined during second and third furrowing of the rabbit egg. Two-cell eggs, collected just prior to onset of second cleavage, were continuously observed in a culture chamber, which was kept at 37 degrees C. Semi-cinematographic techniques were used to photograph progressive stages of cleavage. It was demonstrated that the pattern of cleavage in the rabbit differs from that in the sea urchin, because the blastomeres at the 4-cell stage are arranged crosswise in the former, while they are situated next to each other in the latter. The crosswise arrangement of the blastomeres in the rabbit at the 4-cell stage is a consequence of a 90 degree rotation of the polar axis in one hemisphere of the egg. Subsequently, due to the rotation of the original polar axis in one hemisphere, the third cleavage plane through one half of the egg is transverse to the third cleavage plane through the other half. Evidence is provided to show that the cross wise configuration of blastomeres at the 4-cell stage occurs in other eutherian mammals. It is proposed that this rotational cleavage pattern be recognized as distinct from those of radial, spiral and bilateral.


Pineal and serum melatonin at midday and midnight following pinealectomy or castration in male rats. Melatonin has been extractkd by chloroform from rat serum and quantified by the Rana pipiens tadpole bioassay. Like pineal melatonin, serum melatonin was high at mid-dark and low at mid-light. This finding suggests a diurnal rhythm of serum melatonin in the rat. Serum samples obtained at mid-dark had melatonin levels ranging from 0.02 to 0.05 ng per ml of serum. When rats were pinealectomized, melatonin activity in the serum was abolished. Thus, rat serum melatonin may originate primarily from the pineal. There was no significant change in pineal melatonin content nor in serum melatonin concentrations 7 or 12 days following orchidectomy.


The neural control of contraction in a fast insect muscle. The wing muscles used in singing by the katydid, Neoconocephalus robustus, are extraordinarily fast. At 35 degrees C, the animal's thoracic temperature during singing, an isometric twitch lasts only five to eight msec (onset to 50% relaxation) and the fusion frequency of these muscles is greater than 400 Hz. Stimulating the motornerve to a singing muscle initiates a short (2.5 msec at 35 degrees C), sometimes overshooting depolarization of the muscle fibers. Despite their spike-like appearance, the electrical responses are largely synaptic potentials. The muscle membrane appears to be capable of only weak, electrically-excitable, depolarizing electrogenesis. The short synaptic potentials result in part from rapidly-developing delayed rectification, in part from a low resting membrane resistance (Rm = 162 omega cm2) and a concomitantly short membrane time constant (about 1.5 msec).


Mast cell histamine and ovarian follicular growth in the lizard Anolis carolinensis. The hypothesis is proposed that histamine released from mast cells in the theca of ovarian follicles increases thecal hyperemia and vessel permeability, and thus plays a role in follicular growth in Anolis carolinensis. Mast cells are present in the stroma and theca, and the number of thecal mast cells increases as follicles grow. The levels of histamine in follicular walls varies with follicular size. Histamine causes vasodilatation of thecal vessels. Antihistamine blocks the effects of histamine and, when given alone, stimulates vasoconstriction. Antihistamine also blocks estradiol-induced growth of large follicles. These findings are consistent with the above hypothesis.


Effect of limb regeneration on size increase at molt of the shore crabs Hemigrapsus oregonensis and Pachygrapsus crassipes. Size increase at molt is reduced following multiple limb regeneration in the shore crabs, Hemigrapsus oregonensis and Pachygrapsus crassipes. Limb loss per se does not influence postmolt size. Effect of increasing number of regenerating limbs is additive. Postmolt size is programmed early in the premolt period of the preceding instar and is probably not readily influenced by water uptake mechanics at ecdysis. A simple model for growth, molting, and regeneration in heavily calcified Crustacea is developed from the viewpoint of adaptive strategies and energetic considerations.


DNA-RNA bodies in midgut cells of the stick insect, Bacillus rossius. In the anterior part of the midgut and in the Malpighian tubules of the stick insect Bacillus rossius, about 10% of the epithelial cells develop endonuclear bodies which appear as DNA-RNA masses; in these cells the usual nucleoli are no longer evident. The DNA-RNA bodies are first formed in third instar larvae, become numerous in the fourth instar and persist in adults. In all larval instars and adults a different kind of DNA-body has been noticed in the epithelial cells of the posterior midgut. The DNA-RNA bodies of the anterior midgut and of the Malpighian tubules have been interpreted as the result of somatic gene amplification, whereas the DNA masses of the posterior midgut are likely due to a virus infection.


Initiation of meiotic maturation in Xenopus laevis oocytes by the combination of divalent cations and ionophore A23187. Meiotic maturation was induced in Xenopus laevis oocytes when the external Ca++ or Mg++ ion concentration was raised above 5 mM in the presence of the ionophore. Ionophore-divalent cation-induced maturation appears to be due to the stimulation of the oocyte itself. Cytoplasm of responding oocytes induced maturation when microinjected into ovarian oocytes. Cycloheximid, an inhibitor of progesterone-induced maturation, inhibited the maturational response induced by the ionophore and divalent cations. Ethidium bromide, an inhibitor of the follicular response to human chorionic gonadotropin, had no effect. The possible roles that Ca++ and Mg++ may play in the initiation of maturation are discussed.


In vitro development of t6/t6 embryos.

In vitro development of t6/t6 embryos. Embryos from matings in which approximately a third of the zygotes were expected to be t6/t6, a condition known to be lethal at the egg cylinder stage in vivo, were compared to normal control embryos during post-implantation culture. The percentage success of trophoblast outgrowths was the same in both groups while the experimental group showed a 25% deficiency of embryos with inner cell masses. Those experimental embryos which did have inner cell masses developed comparably to the control group and both groups showed roughly similar numbers of morphologically abnormal egg cylinders. Autoradiography disclosed no deficiency in 3H-thymidine and 3H-uridine labeling in disorganized egg cylinder embryos.


The effects of cold stress on fluctuating asymmetry in the dentition of the mouse. Albino mice (BALB), conceived, born, and raised at 10 degrees C exhibit significant changes in the magnitude of fluctuating dental asymmetry. These results confirm the hypothesis that the dentition responds to the general stress syndrome.


Parathyroid hormone preparations, salmon calcitonin, and urine flow in the South American lungfish, Lepidosiren paradoxa. In the South American lungfish, Lepidosiren paradoxa, injections of salmon calcitonin or bovine parathyroid extract have no effect on serum calcium levels. However, salmon calcitonin elicits a distinct diuresis. Crude or purified parathyroid extract or synthetic parathyroid hormone (1-34 fraction) produce a distinct antidiuresis.


The avoidance of D-tryptophan by the nematode Caenorhabditis elegans. In chemotactic studies employing countercurrent separation the nematode aenorhabditis elegans was found to avoid D-tryptophan with a threshold in the range 10(-4) to 10(-3) M. There was no response to L-tryptophan up to 10(-2) M although it appeared to partially inhibit the response to D-tryptophan.


Polymerization of sperm actin in the presence of cytochalasin-B. The polymerization of globular actin to fibrous actin which occurs when sperm are activated, was not inhibited by cytochalasin-B. The acrosomal filament and its component actin filaments formed in the presence of cytochalasin-B; and once formed, the actin filaments did not depolymerize when exposed to cytochalasin-B.


Normal development of the chick wing following removal of the polarizing zone. The negative results of assays for polarizing activity along the posterior border of the chick wing 24 and 48 hours after removal of the polarizing zone demonstrate that this zone is not regenerated following removal. These results, and the fact that normal wing development can occur after polarizing zone removal from stages 15 through 24 wing buds, indicate that during these stages the polarizing zone has no direct role in normal development of the limb bud. It is speculated that the polarizing zone is effective only during limb induction and that after this time it exists in latent or residual form.


The effect of pancreatectomy on the survival of Anguilla rostrata in different salinities. Pancreatectomized yellow eel survive well in fresh water, but very poorly in sea water. The possiblility is discussed that these observations reflect a direct effect of islet hormones on the osmoregulation.


On the legality of cannabis; the responsibility of the expert witness. The controversy concerning the taxonomic status of the genus Cannabis has now advanced to a stage where the forensic scientist has limitations to his testimony in identification of "marihuana" plant material in jurisdictions where the law defines "marihuana" as Cannabis sativa L. Whether the genus Cannabis is monotypic or polytypic is as yet uncertain, but recent taxonomic reviews weigh heavily toward the existence of three or more species within the genus. The taxonomists or forensic scientists cannot, therefore, positively state for fact that C. sativa is the only species existing within the genus Cannabis. The popular concept of "marihuana" is actually based on the chemical characteristics of the plant Cannabis, rather than on the taxonomic classification. This is evident in its inclusion as a drug or hallucinogenic substance under Federal and local statutes. It is therefore proposed that "marihuana" be redefined legally to include all members belonging to the genus, in jurisdictions where legal definition warrants such an act, or that these jurisdictions follow the format set forth by Federal rulings.


Prostatic acid phosphatase activity in the postcoital vagina. The present results are in general agreement with previous reports on the minimal level of AP activity that should be designated positive and on the period after intercourse in which elevated levels can be demonstrated. In this study 100% of the specimens above 25 KAu were taken within 48 hours of intercourse and 85.7% of these were within 24 hours. For values above 50 KAu, all were within 24 hours of intercourse. A low AP level does not rule out the possibility of recent coitus, particuarly if the woman was menstruating or had douched or used some suppository preparation. These findings also point to the possible interference of certain pathologies in correlating AP activity and time since coitus. As other authors have shown and this study has confirmed, some reactive substance seems to be present in the vagina at all times. For the use of AP assays in the forensic investigation of alleged rape cases, it is suggested that a thorough, accurate history be obtained with regard to douches and suppositories and that the presence of vaginal pathologies be noted. Further research on the techniques used in the forensic investigation of sexually related crimes is proceeding. The large proportion of negative samples within 24 hours of intercourse in this and other studies needs clarification. Other sampling techniques and the quantitative measurement of several different constituents of semen may offer accurate estimates of the time of last intercourse. Large studies with stringent control of the possible variables will further refine this important area of forensic science.


An unusual case of pseudo rape.

An unusual case of pseudo rape. A case has been reported which adds a new and unusual dimension to false rape allegation and gives a heretofore unknown motive for a woman to claim a bogus rape. A female newspaper reporter entered a hospital, stated falsely that she had been sexually assaulted, allowed herself to be interviewed and then examined by the author, and accepted and took medication, all because she wanted to "find out how a rape victim is treated at the new Rape Center and I was pretending to be a rape victim." Rape center workers must be alert to spurious claims of unprincipled and deceitful women.


The examination of disc and pin tumbler locks for tool marks made by lock picks. Microscopic examination of the tumblers of pin and disc tumbler lock cylinders may indicate whether an attempt has been made to pick the lock. If an attempt has been made to pick the lock, it is often possible to determine what type of pick was used. Lock cylinders of five manufacturers, employing tumblers of several different compositions, were examined. The lock cylinders were picked with rake, hook, and bounce picks made of spring steel. The cylinders were disassembled and examined for pick marks. The location and appearance of the marks are discussed. Briefly mentioned are the effects of other types of picks and the effect of ball bearings in the pin wells. Photographs are included to show the pick and wear marks.


Comparison of results for quantitative determination of morphine by radioimmunoassay, enzyme immunoassay, and spectrofluorometry. The quantitative results (accuracy and precision) for determination of opiates by radioimmunoassay (RIA), enzyme immunoassay (EMIT), and spectrofluorometry on split samples are compared. A variety of physiological samples were studied, including random urine from a methadone maintenance clinic and postmortem urine, blood, bile, brain, and lung tissue from heroin-induced or heroin-related deaths. The opiate concentrations detected by the two immunoassay methods were in good agreement with each other in the absence of interfering substances which are believed to react with the antimorphine antibodies. The immunoassay results were in agreement within the relative standard deviation with the fluorometry results in 55% of the urine samples and 80% of the blood samples. The immunological methods are superior to fluorometry for quantitation of morphine in urine samples due to quenching interferences in fluorometry from urine. They were comparable to fluorometry for quantitation of morphine in blood samples.


An improved density gradient system for forensic science soil studies. The construction and use of the apparatus required for an improved density gradient system is described. The system is a combination of existing procedures, resultin in a system more suited for forensic science soil studies. The advantages consist of rapid, simultaneous filling of several tubes with identical density gradients and of the capability to remove individual fractions from the tubes for further study. Disadvantages are that an extra quantity of liquids is required and only a preset number of tubes can be filled at one time.


Firearms discharge residue sample collection techniques. Critical comparisons of Ba and Sb in firearms discharge residue were made on samples collected by three independent collection technqiues. Collection materials studied were transparent adhesive tape, (Scotch Brand), a solution of cellulose acetate in acetone ("Film Lift"), and plastic-shafted cotton swabs wetted with dilute nitric acid. Flameless atomic absorption analyses were performed with a Jarrell-Ash Model 810 instrument equipped with a tantalum strip atomizer. Tape and cotton swabs gave comparable positive indications of residue, with frequencies of 90 and 80%, respectively. The plastic Film Lift gave fewer positives, with a frequency of 50%. With the transparent tape lift, gunshot residue particles are discernible, making nondestructive microscopic identification possible prior to destructive elemental analysis.


Accidental death with tear gas pen gun: a case report. A case of accidental death resulting from a dropped tear gas pen gun is described. Tear gas pen guns can be easily altered to fire regular ammunition and can accommodate a variety of ammunition. Other similar pocket-sized weapons are mentioned.


A review of rejected police candidates.

A review of rejected police candidates. This paper reviews the activities of a Civil Service Medical Review Board which has reviewed the appeals of civil service applicants, particularly for police work, who have been rejected for psychiatric reasons by the hiring authority on the grounds of "mental unfitness." In a 1-1/2-year period, 98 cases have been reviewed. The Board has upheld the applicant in 65% of the cases and the hiring authority in 35% of the cases. Some of the factors resulting in the reversal of the decision of the hiring authority have been discussed. These include insufficient and superficial examination, inappropriate use of test material, attitudinal biases by the examiner, and inadequate reports which do not provide the adequate documentation required by law. It has been the hope of the Board that this review of professional judgment will ultimately impress both hiring authorities and examiners with the defects of the procedures utilized and will encourage them to provide higher quality screening which will be upheld on appeal. To a degree this has been accomplished. Hiring authorities were upheld in only 25% of the cases from September 1973 to March 1974 and 18% from March 1974 to September 1974. This changed radically in the September 1974 to December 1974 period, when hiring authorities were upheld in 60% of the appeals. As has been pointed out, such screening primarily involves review of personality disorders which, by their nature, require thoroughness of knowledge and delicacy of judgment for the formulation of a reasonable conclusion. It is hoped that these lessons will ultimately result in the selection of police officers likely to be successful at their tasks, without arbitrary rejection of those who reasonably merit a trial at work so essential to our society.


Problems surrounding release of persons found not guilty by reason of insanity. The problem of release from institutionalization of those not guilty by reason of insanity is a most troublesome one. Psychiatric criteria for release are to be balanced by what judges see as the needs and protection of society. In 1972, New Jersey in the Maik decision adopted an extremely stringent rule which, if strictly followed, would condemn most NGIs to life imprisonment. Judge Weintraub's demand for assurance that the underlying or latent condition was no longer present put psychiatric examiners in an untenable position. The psychiatrists of the state took the unusual step of preparing a critique of the Supreme Court decision and distributing it to the legal profession through a law periodical. In the interim, the inequities of the Maik rule were recognized and an evolutionary set of standards laid down in the Carter case which provides some flexibility and set standards for conditional release. This clarification will undoubtedly be of great assistance to both courts and psychiatrists in dealing with a complex issue which can never have simple guidelines.


The differential elution of drugs from XAD-2 resin. Biological fluids and tissue extracts prepared according to a previously published method were passed through a column of Amberlite XAD-2 resin for removal of drugs. The differential elution of the adsorbed drugs from the resin was performed by sequential elution of the drugs in four steps. The column was first washed with 30 ml of 0.05M sodium acetate buffer, pH 4.55. Drugs exhibiting acidic or neutral characteristics were then eluted from the column with 100 ml of chloroform in 20-ml aliquots. The column was then washed with 30 ml of 0.1M potassium carbonate, which was discarded. Drugs exhibiting basic characteristics were then eluted from the column with 100 ml of chloroform:isopropanol (3:1) in 20-ml aliquots. Sensitivity of drug detection with this method by thin-layer chromatography was 0.5 mug/ml in a 10-ml sample for nearly all drugs tested.


Diminution and enlargement of the mosquito rhabdom in light and darkness. The rhabdoms of the larval ocelli of the mosquito Aedes aegypti undergo morphological light and dark adaptation over periods of hours. The rhabdom enlarges during dark adaptation and grows smaller during light adaptation. Diminution is exponential, enlargement linear, and rates of change are proportional to log light intensity. Rhabdoms maintained at a constant intensity level off at a constant volume proportional to log intensity. We argue that changes in rhabdom volume after changes in light intensity reflect an influence of light on the turnover of photoreceptro membrane, and that the volumes at which rhabdoms level off represent equilibria between opposed processes of membrane loss and renewal.


Quantitation of conductance pathways in antral gastric mucosa. The magnitude of cellular and shunt conductance of Necturus gastric antral mucosa was studied by (a) comparing the cellular PD response to transepithelial PD response during changes of ionic activity in the serosal bathing solution and (b) by measurement of current spread within the epithelial sheet. Using constant product KCl changes cellular resistance was 6,788 omegacm2 and shunt resistance was 1,803 omegacm2. Deletion of HCO3- from the serosal solution produced similar but quantitatively smaller changes in PD. Using HCO3- deletion cellular resistance was 7,338 omegacm2 and shunt resistance was 1,973 omegacm2. Measurement of current spead within the mucosa avoids changing ionic gradients yet gave very similar results; cellular resistance was 8,967 omegacm2 and shunt resistance was 2,947 omegacm2. The shunt contribution to transepithelial conductance ranged from 75.2 to 79.0%. Shunt selectivity was assessed using KCl dilution potentials, where mucosal dilution gave a small change in tissue PD compatible with an anion/cation selectivity ratio of 1.16 across the shunt, whereas serosal dilution effect was dominated by a PD change across the serosal membrane of the cell.


Oxygen diffusion in biological and artificial membranes determined by the fluorochrome pyrene. Quenching of pyrene fluorescence by oxygen was used to determine oxygen diffusion coefficients in phospholipid dispersions and erythrocyte plasma membranes. The fluorescence intensity and lifetime of pyrene in both artificial and natural membranes decreases about 80% in the presence of 1 atm O2, while the fluorescence excitation and emission spectra and the absorption spectrum are unaltered. Assuming the oxygen partition coefficient between membrane and aqueous phase to be 4.4, the diffusion coefficients for oxygen at 37 degrees C are 1.51 X 10(-5) cm2/s in dimyristoyl lecithin vesicles, 9.32 X 10(-6) cm2/s in dipalmitoyl lecithin vesicles, and 7.27 X 10(-6) cm2/s in erythrocyte plasma membranes. The heats of activation for oxygen diffusion are low (less than 3 kcal/degree-mol). A dramatic increase in the diffusion constant occurs at the phase transition of dimyristoyl and dipalmitoyl lecithin, which may result from an increase in either the oxygen diffusion coefficient, partition coefficient, or both. The significance of the change in oxygen diffusion below and above the phase transition for biological membranes is discussed.


Dual effect of L-glutamate on excitatory postjunctional membranes of crayfish muscle. Iontophoretically applied glutamate produces different excitatory postjunctional permeability changes on separate muscle fibers in a single crayfish muslce. At junctions on some fibers glutamate appears to increase the conductance to both sodium and potassium whereas at others its effect is primarily on the sodium conductance. These results obtained by studying the reversal potential for the extracellularly recorded glutamate potential under conditions of varied extracellular sodium and potassium concentrations.


Resistivity of axoplasm. I. Resistivity of extruded squid axoplasm. Six methods have given squid axoplasm resistivities of from 1.0 to 6.9 times seawater (X SW), so another was tried. A 100-mum platinized electrode was to be inserted from each end of an axion in iso-osmotic sucrose and impedance between them measured vs. separation. But observations that the resistance of axons in sucrose increased steadily ruled this out. Axoplasm from two or three axons was transferred to a glass capillary, 0.6 mm ID, and the 1-kHz series resistance and reactance were measured at electrode separations from 16 to 2 mm. The resistance was linear vs. distance, giving the resistivity, while the reactance was nearly constant, implying constant electrode contributions. Frequency runs from 10 Hz to 30 kHz at 10 mm gave electrode impedances of the form (jomega)-alpha, allowing 1-2% effects on the axoplasm resistivities. In nine experiments, one was discarded for cause, the range and average resistivities were, respectively, 1.2-1.6 and 1.4 times those of artificial seawater (19.7 omegacm at 24.4 degrees C). No single cause for the variability was apparent. These experiments essentially confirm the means and variations of two early experiments with intact axons and recent results with a single internal electrode to give overall resistivities of 1.4 +/- 0.2 X SW.


Resistivity of axoplasm. II. Internal resistivity of giant axons of squid and Myxicola. The specific resistivity of the axoplasm of giant axons of squid and Myxicola was measured utilizing a single metal microelectrode subjected to alternating current in a circuit in which the voltage output varies with the conductivity of the thin layer of fluid at the exposed electrode tip. The average specific resistivity of stellar axons of Loligo pealei was 31 omegacm (1.55 times seawater [X SW]) while for Loligo opalescens it was 32 omegacm (1.30 X SW). Smaller giant axons had a higher average resistivity. Myxicola giant axons had a resistivity of 68 omegacm (2.7 X SW) in normal seawater, and 53 omegacm (2.1 X SW) in a hypertonic high-Mg++ seawater. The temperature dependence of squid axon resistivity does not differ from that of an equally conductive dilution of seawater.


Multiple effects of calcium antagonists on plateau currents in cardiac Purkinje fibers. We studied the influence of Mn, La, and D600 on action potentials and plateau currents in cardiac Purkinje fibers. The Ca antagonists each abolished the second inward current, but they failed to act selectively. Voltage clamp experiments revealed two additional effects: decrease of slow outward current (iotachi) activation, and increase of net outward time-independent plateau current. These effects occurred at inhibitor concentrations used in earlier studies, and were essential to the reconstruction of observed Ca antagonist effects on electrical activity. The inhibitory influence of Mn, La, and D600 on iotachi suggested that iotachi activation might depend upon prior Ca entry. This hypothesis was not supported, however, when [Ca]omicron was varied: elevating [Ca]omicron enhanced Ca entry, but iotachi was nevertheless depressed. Thus, the results suggested instead that Ca antagonists and Ca ions have rather similar effects on iotachi, possibly mediated by changes in membrane surface charge.


Ultraviolet and green receptors in principal eyes of jumping spiders. Spectral sensitivities of cells in principal eyes of the jumping spider Phidippus reqius were measured using techniques of intracellular recording. Three types of cells were found. UV cells had peak sensitivities at 370 nm and were over 4 log units less sensitive at wavelengths longer than 460 nm. Green-sensitive cells had spectral sensitivities which were well fit by nomogram curves peaking at 532 nm. UV-green cells had dual peaks of sensitivity at about 370 and 525 nm, but the ratios of UV-to-green sensitivities varied over a 40: 1 range from cell to cell. Moreover, responses of UV-green cells to flashes of UV light were slower than to flashes of green light. Segregation of receptor types into the known layers of receptors in these eyes could not be shown. It is concluded that jumping spiders have the potential for dichromatic color vision.


Reflection coefficients of permeant molecules in human red cell suspensions. The Staverman reflection coefficient, sigma for several permeant molecules was determined in human red cell suspensions with a Durrum stopped-flow spectrophotometer. This procedure was first used with dog, cat, and beef red cells and with human red cells. The stopped-flow technique used was similar to the rapid-flow method used by those who originally reported sigma measurements in human red cells for molecules which rapidly penetrate the red cell membrane. The sigma values we obtained agreed with those previously reported for most of the slow penetrants, except malonamide, but disagreed with all the sigma values previously reported for the rapid penetrants. We were unable to calculate an "equivalent pore radius" with our sigma data. The advantages of our equipment and our experimental procedure are discussed. Our sigma data suggest that sigma is indirectly proportional to the log of the nonelectrolyte permeability coefficient, omega. Since a similar trend has been previously shown for log omega and molar volume of the permeant molecules, a correlatioo was shown between sigma and molar volume suggesting the membrane acts as a sieve.


Electrophysiological properties of the membrane and acetylcholine receptor in developing rat and chick myotubes. Membrane properties of rat and chick myotubes in various stages of development were studied. Resting membrane potentials (Em) increased from -8 to -55 mV in both rat and chick as the myotubes developed from myoblasts to large multinucleated fibers. In the rat myotubes, this increase was not accompanied by significant changes in specific membrane resistivity or changes in Na+ and K+ ion distribution. Nor have we observed a significant electrogenic component to the resting Em of mature rat myotubues under normal circumstances. A progressive increase in the passive permeability of the membrane to K+ relative to Na+ ions has been observed which can account for the changes in Em with development. In contrast to the changes in the ionic selectivity of the membrane, we have found that the ionic selectivity of the ACh receptor of rat and chick myotubes remains constant during the same period of myotube development.


The kinetics of mycelial growth.

The kinetics of mycelial growth. Based on the assumption that mycelial growth follows the logistic growth law, formulae have been developed to express the growth of fungal colonies under a variety of geometric constraints. Analysis was done of Deppe's (1973) results on surface colony growth, where the mass of the colony grew exponentially during most colonial growth, and of Trinci's (1970) results on submerged "pellet" growth, where the mass of the colony increased as the cube of time during most colony growth. In both cases, the linear dimensions of the colony were increasing linearly while the mass was changing in these quantitatively different manners. It is concluded that these disparate growth behaviours result from different habits of growth; in two-dimensional colony growth a new region of space if invaded by an amount of mycelium small in proportion to the final "carrying capacity" of the region, and in three-dimensional colony growth a region is invaded with an amount of mycelium almost equal to the region's final limiting mycelial mass. Thus, the types of growth law for colony mass which are applicable for a particular organism in a particular physical environment depend critically on the degree to which the invading hyphae initially occupy the space.


Generation times of bacteria.

Generation times of bacteria. Random delays in cell division lead to correlations between the generation times of mothers and their daughters and to a difference between the 'real' and the 'artificial' distributions of generation times. At present there is no satisfactory relation between the two distributions although both are useful in the analysis of growth. In a special case, it is shown that they are similar as long as the coefficient of variation of generation times is small.


The lipids of Agaricus bisporus.

The lipids of Agaricus bisporus. A comparison of the lipid composition of the vegetative and reproductive stages of Agaricus bisporus revealed no major qualitative differences, although quantitative divergence exist. The glycolipids consisted of acylglucoses, acylmannitol, acyltrehalose and a glucosyloxyfatty acid. Two of the acylglucoses corresponded to a tetra-acylglucose and to either a di- or a triacylglucose. The phospholipids were distinctive in that phosphatidylcholine could not be detected. Phosphatidylethanolamine and phosphatidylserine were the major phosphoglycerides. Examination of the neutral lipids revealed the expected array of acylglycerols, free and esterified sterols, and free fatty acids. A substantial amount (26 to 33%) of the fatty acids of the neutral lipids from both sporophore and mycelium were apparently of chain length greater than C18. Linoleic acid was a minor component of the total neutral-lipid fatty acids but comprised about one-half of the total free fatty acids.


Electron microscopy of ascus formation in the yeast debaryomyces hansenii. Ascus formation in Debaryomyces hansenii includes fusion of two cells, usually mother and daughter while still attached to each other, through short protuberances developed from the cross wall between them. Nuclear fusion takes place in the channel connecting the two cells; meiosis apparently occurs in the mother cell. Generally, only one lobe of the meiotic nucleus is surrounded by a prospore wall and it becomes the nucleus of a spore with a warty wall. The rest of the nucleus disappears. The spores germinate by swelling in the ascus and forming one or more buds.


Loss of D-alanine during sublethal heating of Staphylococcus aureus S6 and magnesium binding during repair. Staphylococcus aureus S6 sublethally heated at 52 degrees C for 15 min to 0-1 M-potassium phosphate buffer pH 7-2, lost neither the ribitol teichoic acid of the wall nor the glycerol teichoic acid of the membrane. Hurst et al. (1974) showed that this heating caused 40% loss of the cellular Mg, and we now report the loss of 65% of the ester-bound D-alanine of teichoic acid. Repair from sublethal heat injury, measured by the return of salt tolerance, occurs in a simple no-growth medium provided that the cell concentration is less than 5 x 10(8)/ml. During repair, D-alanine is rapidly synthesized. Fully-repaired cells contain four times more D-alanine than do freshly-injured cells. Magnesium is present in the medium at only 3 x 10(-6) M, yet the cellular Mg concentration returns to normal within 1 h of incubation, even in the presence of EDTA. The results suggest that repair occurs in two stages. Soon after injury, in the absence of the competitive effect of D-alanine, Mg is strongly bound to teichoic acid. In repaired or uninjured cells Mg is less strongly bound. The implications of these findings are discussed in relation to the cation-binding function of teichoic acid.


The effects of aeration on glucose catabolism in Penicillium expansum. Polyacrylamide-disc gel electrophoresis and quantitative enzyme assays showed that the pathways of glucose catabolism and secondary metabolism in Penicillium expansum were dependent on the degree of aeration of the cultures. The isoenzyme patterns and specific activities of aldolase and succinate dehydrogenase indicated that glycolysis and the tricarboxylic acid cycle operated under conditions of both limited and efficient aeration (i.e. in cultures grown statically or on an orbital shaker). At high levels of aeration the growth rate was faster and synthesis of extracellular pectolytic enzymes was enhanced, whilst the activities of glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase showed that the pentose-phosphate shunt was important in glucose catabolism during the trophophase of growth. In contrast, under conditions of low aeration this latter pathway was virtually undetectable, growth was slower, pectolytic enzyme production low and large concentrations of secondary metabolites (6-methylsalicylic acid, patulin and citrinin) accumulated.


The entry of D-ribose into some yeasts of the genus Pichia. The utilization of D-ribose by yeasts of the genus Pichia was examined with respect to aerobic growth, respiration and entry of ribose into the cells. Pichia etchellsii (CBS2011) could respire D-ribose, but not use it for aerobic growth. Pichia fermentans (CBS187) neither respired nor grew on D-ribose, though it entered the cells of this yeast either by simple diffusion, or possibly, by the D-glucose carrier, this having a very low affinity for D-ribose. Pichia pinus (CBS5097) respired and grew on D-ribose; kinetic evidence is given for this yeast having two ribose carriers, one inducible and the other constitutive.


Assimilation of exogenous fructose, aspartate and some organic acids during the growth of methylotrophs. The percentage of bacterial carbon that was derived from exogenous labelled compounds present in the medium during the growth of some methylotrophs on trimethylamine or on non-C1 compounds was determined. Less than 10% of bacterial carbon was derived from acetate during the growth of the obligate methylotrophs 4B6 and C2A1, and of the restricted facultative methylotroph PM6; the other restricted facultative methylotroph W3A1 gave a value of 18%. Corresponding values for three typical facultative methylotrophs growing on trimethylamine were 41, 42 and 52%. Aspartate, fructose, pyruvate and succinate made only a small percentage contribution (0-4 to 12%) to bacterial carbon in 4B6, C2A1, W3A1 and PM6. Washed suspensions of 4B6, C2A1, W3A1 and PM6, all grown on trimethylamine, assimilated labelled acetate only in the presence of trimethylamine and there was a linear relationship between the amount of acetate assimilated and the amount of trimethylamine oxidized. Organisms 4B6, C2A1, W3A1 and PM6 assimilated 14C from labelled acetate predominantly into lipid (except PM6), glutamate, arginine, proline and leucine, whereas the typical facultative methylotrophs assimilated 14C from acetate into lipid, nucleic acid and all the protein amino acids. These results are consistent with the presence of a deficient tricarboxylic acid cycle in the obligate methylotrophs and in the restricted facultative methylotrophs.


Metabolism of the germinating sclerotium of Claviceps purpurea. The concentration of free amino acids, particularly alanine, altered as stromata developed on germinating sclerotia. Lipid reserves in the sclerotium provided the principal carbon and energy source, and the nutrients required for stomatal growth appeared to be provided by the sclerotial tissues immediately beneath the point of attachment of the stoma. Alkaloid did not disappear from the sclerotia during germination. Very high levels of polyol, particularly mannitol, were attained in the stromata as germination progressed; the synthesis of polyol was usually accompanied by that of soluble sugars, notably glucose. In an attempt to ascertain the role of mannitol in germination, the relationship between polyol and soluble sugars was investigated in excised stromata after their submergence in buffered media containing a variety of soluble carbohydrates. Mannitol was synthesized under these conditions by way of phosphorylated intermediates, and chiefly in the capitulum, after rapid, and probably passive, absorption of the exogenously supplied sugar. The tissues equilibrated rapidly with the supplied carbohydrate, whose concentration was maintained by further uptake whilst mannitol was being synthesized. The concentrations of assimilated glucose and synthesized mannitol tended toward the same value during incubation and the results suggested that the synthesis was compartmentalized within the stromata. Very little exogenously supplied mannitol was assimilated.


Inhibition of protein synthesis by D-threo-chloramphenicol in the laboratory and nodule forms of Rhizobium lupini. Protein synthesis by both laboratory-grown bacteria and isolated nodule bacteroids of Rhizobium lupini (strain WU8) is inhibited by D-threo-chloramphenicol, the bacteroid form being the more sensitive to the antibiotic. A comparison between the two forms of the uptake of [14C]chloramphenicol showed that the bacteria always attained a lower intracellular chloramphenicol concentration. It is proposed that the sensitivity difference is due to a difference in membrane permeability between the two forms.


Inhibition of multiplication of tobacco mosaic virus in protoplasts by antibiotics and its prevention by divalent metals. At concentrations that inhibit bacterial growth, some antibiotics including gentamicin completely inhibited virus multiplication in protoplasts, and other antibiotics partially inhibited virus multiplication. The inhibition caused by each antibiotic was largely prevented by adding a divalent metal; MnC1(2) was more effective than CaC1(2) and other salts of divalent metals when added at 10 mM to the incubation medium. When added immediately after infection, 1 mug/ml of gentamicin halved the final virus concentration and 3 mug/ml completely inhibited virus multiplication, although 10 mug/ml was required to stop bacterial growth. Gentamicin inhibited virus multiplication even when added 24 h after virus inoculation. Also, when protoplasts were exposed to gentamicin for only 1 or 2 h, either immediately after inoculation or 2 h later, the virus concentration was considerably decreased. Gentamicin seemed not to affect virus multiplication in whole plants. Sap from Dianthus barbatus also strongly inhibited virus multiplication in protoplasts but, unlike gentamicin, it acted in the presence of MnC1(2). By contrast, chelating agents such as 1 mM-EDTA or 5 mM-potassium citrate was strong inhibitors of virus multiplication that were inactive in the presence of MnC1(2). It is suggested that gentamicin and other antibiotics may chelate metals from the protoplast membranes, thus disorganizing their function and affecting virus multiplication.


Immunomodification and the expression of virulence in mice by defined strains of Semliki Forest virus: the effects of cyclophosphamide. Mice were infected i.c. or i.p. by an avirulent clone of Semliki Forest virus at various times before or after the i.p. administration of a single dose of cyclophosphamide. Consequent changes in the patterns of viraemia and antibody production are interpreted in terms of the potentiation of the initial infection or the decreased resistance to subsequent lethal challenge. These change demonstrate two distinct modes of immunomodification determined by the time of cyclophosphamide administration in relation to virus infection, but not correlated with the death or protection of individual mice. These results are discussed in relation to the early regulatory functions of T and B cells which may influence the expression of virulence but escape conventional assay during the critical first 3 days following infection.


A latent guinea pig herpes-like virus: isolation and envelopment. A guinea pig herpes-like virus (GPHLV) has been isolated from randomly selected guinea pigs. This virus is serologically related, if not identical, to the guinea pig herpes-like virus isolated by Hsiung-Kaplow. The frequency of latent infection in guinea pigs was found to be highly variable among animals of the same commercial origin. Ultrastructural studies have shown that the morphological development of this virus was similar to that reported for other herpes viruses in the early stages, but frequently differed at the envelopment stage. In the cytoplasm, virus particles were associated with electron-dense zones from which they acquired a thick and rough envelope.


Hydrophobic chromatography of hepatitis B surface antigen on 1,9-diaminononane or 1,10-diaminodecane linked to agarose. A series of omega-aminoalkyl-agarose differing in the number of carbon atoms in the alkyl chains was prepared and used for chromatography of hepatitis B surface antigen (HBSAg). HBSAg was separated from the major part of serum proteins by adsorption to columns of 1,9-diaminononane or 1,10-diaminodecane linked to agarose beads (Sepharose 4B or 2B) followed by elution with 4 M-NaSCN.


Studies of temperature sensitive mutants of bacteriophage Qbeta, defective in both replication and translation. Temperature sensitive mutants of bacteriophage Qbeta have been isolated which fail in the synthesis of their virus RNA at the non-permissive temperature (42 degrees C). Nine mutants have been studied in some detail. Cells infected with these mutants at 37 degrees C and incubated long enough to produce substantial amounts of Qbeta RNA cease Qbeta RNA replication when shifted to 42 degrees C. The mutants can be classified into 3 groups according to the amount of Qbeta RNA replicase activity exhibited in extracts from infected cells isolated at various times after shift to 42 degrees C: in group 1 mutants, enzyme activity is the same, regardless of the time of isolation after shift; in group 2 mutants enzyme activity increases with time of isolation after shift; in group 3 mutants, enzyme activity decreases with time of isolation after shift. Synthesis of all virus proteins is suppressed at 42 degrees C in cells infected with group 2 of group 3 mutants. In cells infected with group 2 mutants, synthesis of Qbeta RNA replicase subunit beta is increased, but synthesis of other virus proteins is depressed at 42 degrees C. The inhibition of virus RNA and protein synthesis is reversible. A detailed analysis of these experiments suggests that a defective Qbeta RNA replicase is involved in the inhibition of both virus RNA and protein synthesis.


Inhibition of the replication of influenza A and B viruses by a nucleoside analogue (ribavirin). A synthetic nucleoside analogue 1-beta-D-ribofuranosyl-1,2,4-triazole-3-carboamide (ribavirin or RTCA) inhibits the replication of tissue culture of influenza B virus and also a wide range of influenza A viruses of human, animal and avian origin. The synthesis of influenza virus-induced antigens and also structural and non-structural polypeptides is inhibited by RTCA as detected by immunofluorescence and by pulse labelling experiments with [35S]-methionine. The inhibitory effects of RTCA on influenza A virus replication in tissue culture is reversed by a molar excess of guanosine or zanthosine which suggests that the compound acts at an early stage of virus RNA synthesis prior to the utilisation of the latter nucleosides. A possible inhibitory effect of RTCA on cellular DNA replication is not excluded.


Structure and position of a complex chromosomal aberration in bacteriophage P2. The P2 phage mutation vir56, like the previously studied vir22, is the result of an unequal replacement of a chromosome segment with non-homologous DNA. The end positions of the replacements are essentially the same in the two mutants, whereas the lengths of the replacements are quite different. A third chromosomal aberration, del3, has similar structure and position. These results strengthen the suggestion that the left ends of these three aberrations coincide with the point of exchange in integrative recombination.


Psychoses associated with marijuana use in Thailand. Marijuana use among the 45,000 Air Force troops stationed in Thailand during the period September 1971 to September 1972 was extensive. Nevertheless, only five cases of prolonged psychosis associated with marijuana use in this population were referred for psychiatric evaluation. These cases resembled several types of adverse reactions previously described in the literature: one case of a "marijuana psychosis"; one case of an "organic marijuana syndrome"; and three cases of "marijuana-mobilized functional psychosis." With the exception of the patient with the "marijuana psychosis," this small group of men had either borderline or schizoidal premorbid personalities. Other more transient psychotic episodes appear to go unreported by the troops because of the rapid clearing of symptoms and the punitive policy of the Air Force toward drug abuse.


Subject expectancy and environmental factors as determinants of psychedelic flashback experiences. This study assessed the roles of expectancy and autonomic arousal in inducing psychedelic flashbacks under conditions of mild sensory deprivation. Subjects with and without previous flashbacks participated. During the first experimental session, subjects were given a drug which they were told would induce flashbacks, and during the second, a drug which was alleged to induce only autonomic arousal. Ephedrine sulfate (causing autonomic changes) or placebo actually was given in counterbalanced order. Subjects of both groups experienced many more psychedelic sensations when they expected flashbacks. Drug effect was nonsignificant. These findings support the view that flashbacks are not "caused" by psychedelic drugs, but by the tendency of some drug users to mislabel and selectively attend to relevant aspects of naturally occurring altered states of consciousness.


Psychiatric crisis. A comparison of schizophrenic and nonschizophrenic patients. Thirty-nine patients (23 nonschizophrenic and 16 schizophrenic people), who were hospitalized on a short term, crisis intervention ward, were extensively interviewed to discover whether the crisis precipitants and the crisis experience differed for the two groups. As opposed to the schizophrenic individuals, the nonschizophrenic, "distraught" patients led orderly lives and were more likely to be in problematic developmental life stages (i$, late adolescense) or to be physically ill. For the distraught patients, the precipitating events were clearer and were more likely to involve interpersonal or narcissistic loss (i.e., the end of a romance), overt anger was less likely to be expressed, and parental figures were less likely to be involved. Both the nonschizophrenic and the schizophrenic people were thought to be chronically vulnerable to external stress. A phenomenological description of their psychopathology was included to explain, in part, their vulnerability. Suggestions about treatment approaches were developed.


Peculiarities in the endocrine response to insulin stress in early infantile autism. Autistic children subjected to the stress of insulin-induced hypoglycemia showed slower recovery of blood glucose, and faster and intractable cortisol response in the 3 hours following the stress. These data suggest that autistic children over-react to this stressor and support clinical evidence of stress intolerance. It is suggested that this peculiarity may be implicated in an explanation of the abnormal behavior seen in this disorder.


Effects of repeated administrations of a comprehensive neuropsychological battery among chronic epileptics. Effects of repeated administrations of the neuropsychological battery originated by Halstead and developed by Reitan were assessed by administration of the battery on four occasions at 6- to 12-month intervals to 17 epileptics with stable neurological dysfunction. Changes in drug regimen complicated interpretation to some degree, but it appeared that: a) the majority of the neuropsychological measures did not demonstrate significant practice effects; and b) there were statistically and clinically significant practice effects on some of Halstead's most sensitive measures (Category Test, Tactual Performance Test--Localization, Impairment Index). In addition, the question was raised as to whether or not the Wechsler Adult Intelligence Scale may be more effected by the administration of anticonvulsants than are many of the other neuropsychological procedures. Caution was urged in interpretation when the battery is used on a repeated basis.


A case of prolonged, reversible dementia associated with abuse of electroconvulsive therapy. Standards for the use of electroconvulsive therapy (ECT) are being considered in Massachusetts. While the relative safety of ECT is sometimes used to justify its extensive use, ECT is abused in some cases, causing prolonged deficits in sensorium. A case of an ECT-induced, prolonged, reversible dementia is presented as an example of present abuses and the need for standards.


Successful lithium treatment of transvestism associated with manic-depression. A case of transvestism in a 24-year-old manic-depressive man is described. The behavior had been maintained for 2 years and disappeared soon after lithium treatment was begun. It has not returned during the first year on lithium. Dynamic and behavioral explanations for this unusual therapeutic response are considered. The dynamic explanation involves the assumption that the transvestism was perpetuated by mood-dependent motives that were eliminated by lithium. The behavioral explanation involves the assumption that the manic state itself became an intermittent reinforcer for the transvestism, and the lithium, by eliminating the mania, created a relatively permanent extinction period.


Effects of thiamine antagonists on nerve conduction. I. Actions of antimetabolites and fern extract on propagated action potentials. To assess the hypothesis that thiamine is directly involved in the permeability changes at the sodium channel during nerve conduction, the effects of thiamine antagonists on lobster giant axon resting and action potentials were determined. Thiamine antimetabolites, in millimolar concentrations, reversibly decreased the maximum rate of rise and amplitude of the action potential while increasing its duration. In particular, thiamine tert-butyl disulfide (TTBD) elicited the formation of pronounced shoulders during repolarization, lengthening the action potential by 2-50 times, depending on dose. Antimetabolites also depolarized the resting membrane, but this change was poorly reversible and may indicate a dual mechanism for antimetabolite action. An extract of the fern, Pteris aquilina, reversibly decreased the maximum rate of rise of the action potential and depolarized the resting potential. It also elevated and prolonged the action potential after-depolarization, sometimes causing repetitive activity. The strength of these actions was correlated with the antithiamine potency of the extract, and was diminished by addition of thiamine to the extract.


Effects of thiamine antagonists on nerve conduction. II. Voltage clamp experiments with antimetabolites. Thiamine antimetabolites were externally applied to voltage clamped squid giant axons to investigate the possible role of thiamine in nerve conduction. Phenylthiazinothiamine, in concentrations as low as 250 muM, reduced peak early current and steady-state current, with the depression of the former being two to five times greater than that of the latter. Peak transient and steady-state conductances were about equally depressed by thiamine tert-butyl disulfide (2 mM) and L-586944-00P07 (5-10 mM). None of the antimetabolites produced an appreciable change in the kinetics of Na+ activation, K+ activation, or Na+ inactivation. Thiamine itself, applied externally up to 30 mM, had no appreciable effect on either the magnitude or time course of the ionic currents. Although these data are consistent with the hypothesis that thiamine may be involved in nerve conduction, they probably reflect a nonspecific stabilizing interaction of this class of compound with the axon membrane. Taken in this light, the hypothesis that thiamine plays a direct role in Na+ channel permeability changes must be reevaluated.


Ultrastructural correlates of interneuronal function in the abdominal ganglion of Aplysia californica. The synaptic inputs and outputs of the major interneuron L10 of the abdominal ganglion of Aplysia were studied using an intracellular staining technique for the electron microscope. The sites of both the chemical synaptic input and output of L10 are localized to the dendritic arborizations that arise from the axon in the ganglion neuropil. Thus, the interneuronal functions are mediated at the dendritic processes and could occur in the absence of spiking in the axon and cell body. The sites of L10 synaptic output are presumed to be at aggregations of vesicles and mitochondria in the dendrites.  The synaptic vesicle content of L10, a cholinergic neuron, with many large dense vesicles resembles that described for serotonergic cells in Aplysia, making distinction of synaptic pharmacology by ultrastructure difficult. Focal membrane specializations with a clear synaptic cleft were not observed between L10 and its large population of postsynaptic cells. In contrast, clear focal input sites were frequently found on L10. Gap junctions, sites of probable electrical coupling between L10 and other neurons, were also found. These observations are discussed as evidence that many synapses do not have focal specializations.


Integration in the crayfish antennal neuropile: topographic representation and multiple-channel coding of mechanoreceptive submodalities. (1) Response patterns of interneuron populations in the antennal neuropile of the crayfish have been investigated by extracellular recordings made with a single electrode. Mechanical stimuli of the antennae are divided into submodalities and topographically represented. The submodalities include large movements of the entire antenna, directional aspects of movements and vibrations, and vibratory stimulation up to click repetition rates of 100. (2) Interneuron output is always patterned, ranging from simple bimodal types to complex multimodal patterns that extend over 40 msec. The interneuron output is "noisy" due to short- and long-term fluctuations in sensitivity producing temporal fluctuations in both output probability and output patterns. The response latencies both within and between populations cluster around several fixed latencies. (3) The axons of a group of neurons, sensitive to the same submodality, are located together and consequently can be recorded with a single electrode. Responses from the interneurons composing a population are similar in response to nonoptimal stimulation, but are synchronized and of high probability to optimal stimulation.


Physical and physiological properties of the crayfish antennal flagellum. (1) Mechanoreceptors in the crayfish antennae are divided into four functional categories: vibration (13%), bidirectional displacement (19%), unidirectional displacement (45%), and position (23%) receptors. The distribution of receptors along the length of the flagellum follows a logarithmic progression, decreasing from about 40% at the base to less than 5% at the tip. (2) Vibratory stimulation of the antennae was found to induce a traveling wave. Because of an impedance gradient along the length of the flagellum, the traveling wave moves most efficiently from base to tip. The wave was observed to travel at an average velocity of 6.0 m/sec. (3) Large deflections of the tip are not uniformly transferred to the base, but decrease logarithmically. This due to the existence of the impedance gradient. (4) Receptor output probability was found to be greatest when low frequency/high intensity stimulation was applied to the flagellar base. (5) Characteristics of large (2 cm) posterior-going deflections of the flagellar tip that are effective in producing response differences are displacement: (a) amplitude, (b) velocity, and (c) acceleration.


Reversal of delayed myelinogenesis in experimental hypothyroidism. Neonatal hypothyroidism has been shown to induce delayed myelinogenesis in the developing rat brain. This delay in myelin formation is most prominent during the critical 3 - 4 week postnatal period and the heavy myelin fraction is more selectively affected. The experimental animals, however, continue active myelin formation and by 6 weeks post natum, they do not differ significantly from littermate controls. Myelin protein analysis by SDS acrylamide gels and densitometer methods revealed a decreasing proportion of high molecular weight protein and no significant change in either proteolipid or basic protein in developing myelin. The data suggest that neonatal hypothyroidism induces a reversible delay without qualitative change in myelinogenesis.


Experimental pneumococcal meningitis. Effects of neuraminidase and other pneumococcal constituents on cerebrospinal fluid in the intact dog. The intracisternal administration of a Type I pneumococcus to mongrel dogs resulted in spinal fluid abnormalities and clinical course and outcome similar to those of meningitis in humans. In order to define the pathogenic role of pneumococcal neuraminidase and other pneumococcal extracts in experimental meningitis, the following preparations were derived from the same Type I pneumococcus: crude neuraminidase, partially purified neuraminidase, heat-inactivated crude neuraminidase, and heat-killed pneumococci. These preparations were administered intracisternally daily for 5 days to a series of mongrel dogs. These substances did not produce clinical morbity similar to that observed in infected animals, even though there was significant decrease in the NANA content of cortical brain subcellular structures in the neuraminidase-treated dogs. It was concluded that the substances investigated were not responsible for morbidity and mortality in experimental pneumococcal meningitis. Both heat-killed pneumococci and the crude neuraminidase preparation elicited significant alterations in spinal fluid glucose and protein concentrations which were similar to those recorded in infected animals; however these abnormalities were not associated with significant morbidity. It is proposed that spinal fluid glucose and protein abnormalities may not be directly linked to brain damage or dysfunction in this experimental model, or in man.


Quantitative oxidative enzyme histochemistry of the spinal cord. Part 1. Distribution of enzyme activity in anterior horn cells. Cytophotometric measurements of the activities of 5 oxidative enzymes (succinate, malate, lactate, NAD+-linked isocitrate and NADH dehydrogensases) have been made in anterior horn cells of the lumbar and cervical spinal cord of the rabbit. The thickness of tissue sections was measured by an interference microscope and various optical and chemical precautions were taken to diminish the possible errors that might be involved in cytophotometry. The findings of the study indicated a unimodal distribution of the activities of all of the enzymes studied in anterior horn cells, though there was a wide range of enzyme concentration among different cells. Thus the findings in the rabbit are consistent with the "constant proportion" hypothesis of the activity of certain oxidative enzymes, and are contrary to a previous finding that there may be two populations of succinate dehydrogenase-containing anterior horn cell.


Quantitative oxidative enzyme histochemistry of the spinal cord. Part 2. Relation of cell size and enzyme activity to vulnerability to ischaemia. Cytophotometric measurements of the activities of 5 enzymes (succinate, malate, and NAD+-linked isocitrate dehydrogenases from the tricarboxylic cycle, lactate dehydrogenase from the Embden-Meyerhof pathway, and NADH dehydrogenase) were correlated with cell volume for neurones in the anterior horn of rabbit lumbar and cervical spinal cord. The data for succinate and isocitrate dehydrogenases indicated that these enzymes were at higher concentrations in the smaller neurones, which consist largely of interneurones. No preferential localization to particular sizes of cell could be assigned to the other enzymes studied. The relationship between enzyme distribution patterns and their possible role in contributing toward susceptibility to ischaemia of particular sizes of neurones is discussed.


Appearance of acetylcholinesterase and creatine kinase in plasma of normal chickens after denervation. Evidence that acetylcholinesterase (AChE) activity is released from normal chick embryonic muscle fibers and from muscles of chickens with inherited muscular dystrophy suggested that denervated chick muscles, which have AChE properties similar to dystrophic muscles, would also release AChE. Bilateral denervation of the breast and wing muscles of normal chickens was followed by the appearance of AChE activity, distinguished from plasma cholinesterase by differential substrate hydrolysis, inhibitor sensitivity, and electrophoretic migration. Plasma creatine kinase (CK) activity was also elevated after denervation.


A comparison of the structure of small blood vessels in normal, denervated and dystrophic human muscle. A light- and electron-microscopic study of the small arterial vessels and capillaries in muscle from 20 patients with Duchenne muscular dystrophy failed to adduce any direct morphological evidence that the necrobiotic muscle lesions in this disease are produced by muscle ischaemia. However the electron-microscopic studies showed that the basement membrane width in 3 out of 4 cases of Duchenne dystrophy so studied was significantly less than that or normal control material. In further case of Duchenne dystrophy, selected for study because some vessels in the biopsy muscle were surrounded by small round cell infilitrates, the basement membrane width was significantly greater than that in the normal control material. In the single case of spinal muscular atrophy studied, the basement membrane width was also significantly less than the control measurements. The possible relationship of these observations to the "ischaemic" theory of the pathogenesis of muscular dystrophy is discussed.


The effects of glycerol on cerebral ultrastructure following experimentally induced cerebral ischemia. Ultrastructural changes in cerebral tissue subjected to temporary occlusion on the  right middle cerebral artery for intervals of 30 min, 1, 2, 3, and 4 hr were studied after daily injections of 10% glycerol in saline. These changes were compared with previously reported data from untreated animals. The extent of tissue involvement was appreciably less in the glycerol-treated group as evidenced by the reduction of intracellular edema and fewer changes in the membranes of ultrastructural elements (mitochondria, endoplasmic reticulum, Golgi complex, and plasmalemma) known to be essential for cellular metabolism and function in the central nervous system.


A memory defect in uremic encephalopathy. It has been demonstrated that anesthesia primarily affects the reticular activating system and psychological studies on patients undergoing anesthesia demonstrated a verbal memory defect. This study was performed in order to determine whether metabolic  (uremic) encephalopathy follows the Jacksonian dissolution hypothesis and disrupts cortical function or whether it acts like an anesthetic, causes dysfunction in phylogenetically older systems and thereby produces a memory defect. Twenty-four uremic subjects were tested for memory function, language function, and intellectual function, and compared to 12 control subjects. The greatest difference between the groups was in immediate memory function suggesting that uremia probably acts in a manner similar to anesthesia (by causing dysfunction in the reticular activating system). It is postulated that poor arousal interferes with rehearsal and rehearsal is probably an important component of immediate memory.


The electrocardiogram in infratentorial infarcts. Sixty-nine patients with infratentorial infarcts were studied with respect to associated electrocardiographic (ECG) abnormalities. ECG changes were encountered in about 70% of the patients, the most frequent abnormalities being arrhythmias, conduction disturbances and ST-T changes. No relationship was found between the localization of the brain-stem lesion and the accompanying ECG pattern. It is concluded that ischaemic lesions within the central nervous system do not per se affect the ECG and that associated ECG changes are merely coincidental, reflecting the same basic vascular disease.


Profile of multiple sclerosis in the bombay region. On the basis of critical clinical appraisal. Using internationally accepted strict clinical criteria, 30 patients with probable multiple sclerosis (MS) fron the Bombay region have been described. They were personally studied and followed up over a period of 15 years. In addition, 9 patients with neuromyelitis optica and 6 with a mixed neurological picture of MS and neuromyelitis optica have been described. As in Japan, the neuromyelitis optica type of presentation was relatively more frequent in our material than in the West. In this small series MS was more frequent in patients with a better socio-economic status, in the Parsee community and in patients with a fair complexion, whereas neuromyelitis optica was more frequent in patients with poor socio-economic status. A relatively high proportion of patients (nearly half of the MS patients with optic nerve involvement and two-thirds of the MS--neuromyelitis optica group) had bilateral optic nerve involvement. Except in 2 patients, the tempo and course of the disease in our patients with MS was comparable to that seen in the West. In 3 patients with MS the initiation of symptoms or appearance of fresh symptoms was related to vaccination. In addition to the above 45 patients, 29 other cases of possible demyelination have been reviewed. Nine of these had one or more remission and relapse but in the same site as the first episode. Seventeen had a solitary episode of spinal cord or brainstem disturbance with some remission and 3 had multiple lesions but without remission or clear dissemination in time. In the absence of a specific diagnostic test or autopsy, such atypical cases will remain unclassified. To conclude, MS does occur in the Bombya region and elsewhere in India but the incidence is much less than in the West. Further studies and especially careful follow-up of atypical cases may show that the prevalence is higher than it seems today.


The neurotoxic effects of triethyltin (TET) sulfate on myelinating cultures of mouse spinal cord. Well myelinated cultures of mouse spinal cord, exposed to varying concentrations of triethyltin sulfate, were examined at different time intervals by light and electron microscopy. At a high concentration of TET (10(-6)M) for 1-2 hours, the myelin sheaths and cells showed marked degenerative changes. At lower concentrations of TET (10(-7)-10(-9) M) intramyelinic and other types of vacuole formation were seen; however, these lesions were always accompanied by changes in the perikarya, dendrites and axons of neurons and in the astrocytes. Also, there was an apparent increased number of neurofilaments and neurotubules in many axons. The findings are discussed in relation to the lesions induced in the experimental animal by alkyl tin intoxication.


The sural nerve in familial dysautonomia. In familial dysautonomia there are malfunctions of motor, sensory and autonomic systems. The sural nerve has reduced transverse fascicular area, diminished numbers of myelinated axons (particularly those of small diameter) and very few non-myelinated axons. Catecholamine containing endings are not found in accompanying arteries. These changes are compatible with reduced neuronal populations described in sympathetic and sensory ganglia. The observed pathology accounts for many of the clinical features of the disease and suggests an abnormality in intrauterine development.


Brain ultrastructure in Reye's syndrome. Cerebral biopsies were obtained for electron microscopy 48 and 72 hours after the onset of encephalopathy from a child with severe Reye's syndrome. Gravely ill at the time of craniectomy to relieve cerebral hypertension, the child survived and recovered good brain function; therefore, the biopsy findings appear to reflect the organelle pathology of the brain at a severe yet reversible stage in the disease process. The cardinal ultrastructural changes in the brain in Reye's syndrome are astrocyte swelling and partial deglycogenation, myelin bleb formation and universal injury of neuron mitochondria. The mitochondrial injury consists of matrix disruption with moderate but not massive swelling. Dilatation of rough endoplasmic reticulum and nuclear changes occurred only in neurons with severely altered mitochondria. The organelle pathology of the brain in this case did not resemble the organelle pathology of the brain in human "hepatic encephalopathy" or in experimental ammonia intoxication in primates. The mitochondrial ultrastructure of the cerebral neurons resembled the unique mitochondrial ultrastructural changes seen in the liver parenchyma in Reye's syndrome.


Neurofibrillary changes following childhood lead encephalopathy. This report details the findings in a patient who survived severe lead encephalopathy at age 2 1/4 years, to die 42 years later in a state of severe mental deterioration. The brain revealed diffuse cortical atrophy, most severe in the temporal lobes, followed by hippocampi, amygdaloid nuclei and frontal cortex. Numerous pyramidal cells of the forebrain grisea contained Alzheimer's neurofibrillary tangles. The remaining pyramidal cells of the hippocampi exhibited granulo-vacuolar degeneration. Many senile plaques were present predominantly in the atrophic temporal cortex. Electron microscopic examination revealed many 800 A twisted tubules in the tangles. Atomic absorption spectrophotometry disclosed a tenfold increase of lead in frontal and temporal cortices as compared to suitable controls. The possibility that toxic levels of lead in any form could result in the formation of Alzheimer's fibrillary tangles is discussed.


The structural basis for electrotonic coupling in the avian ciliary ganglion. A study with thin sectioning and freeze-fracturing. Each "ciliary" neurone in the ciliary ganglion of adult birds receives its innervation from a single myelinated fibre of the oculomotor nerve by means of a dual mode of synaptic action, electrical and chemical. The preganglionic fibre branches repeatedly around the postganglionic axon but the extra-cellular compartment is large. The preterminal fibres, most of which are unmyelinated, end with large boutons on the axon hillock, a few on short dendrites and on the portion of the perikaryon of the ciliary neurone from which the axon emerges. This synaptic apparatus is enveloped by a glial sheath, mainly consisting of satellite cell bodies and loose myelin lamellae. The nonsynaptic portion of the ciliary perikaryon is covered by a sheath consisting mainly of compact myelin. The ciliary neurone has an initial axon segment like that of C.N.S. neurones. The area of each neurone apposed to boutons measures about 16,000 mum2. Approximately 9 percent is specialized for chemical transmission and 0.17 percent for electrical transmission. Each neurone has about 280,000 gap junctional particles. Assuming that each particle represents one channel, the electrical resistance provided by these junctions is estimated to be of the order of 100 k omega. The electrical coupling between the preganglionic fibre and the ciliary neurone may therefore be of resistive nature.


Cation-dependent structures associated with membranes in the rat central nervous system. As observed by high magnification electron microscopy, potassium ions induce osmiophilia at the extracellular side of triple layered plasma membranes in the central nervous system of the rat. In contrast, sodium ions induce a widening of the intracellular lamina of these membranes, and do not result in observable extracellular deposits. The observations suggest the existence of potassium and sodium ion-selective structures associated with opposite surfaces of the neuron membrane. Use of the fixative vehicle as a cytochemical reagent is proposed.


Organotypic development of the organ of Corti in culture. The preservation and development of the innervation pattern in the organ of Corti have been studied in culture up to 27 days in vitro. The explants were obtained from the newborn mouse. Segments of the cochlear duct dissected together with the appropriate sectors of the spiral ganglion may retain their structural organization for about two weeks. Maturation of some nonneuronal elements which occurs during that time is followed by a subsequent regression of the organ. Only a fraction of the explanted neurons survive. However, the surviving neurons, if connected with the hair cell region, maintain a complex peripheral innervation pattern that contains all the major fibre components which characterize the normal pattern in a young mouse. The peripheral innervation pattern in culture seems largely composed of preserved fibres, that is, of fibres which at the time of explantation have already ramified within the organ of Corti. Nonetheless, there is evidence for growth or maturation, in culture, of at least some peripheral processes of the spiral neurons. Thus, only in older cultures is the innervation of the apical tip established. Likewise, it is only in older explants that the inner spiral bundle becomes prominent. Spiral neurons survive in culture in several modes. Most frequently, the central process is altogether absent and the neuron is effectively a unipolar cell which maintains only the peripheral process. A distinct minority of neurons is bipolar possessing both the peripheral process and a central axon which grows freely, though no central target is present. A neuron may survive also as a unipolar or, rarely, as a bipolar cell with no processes entering the organ of Corti. The observations imply that (1) most or all major fibre systems in the organ of Corti carry components of spiral neuron origin; (2) a small population of spiral neurons innervating a short segment of the organ contributes importantly not only to the radial but also to the spiral innervation of the segment.


Observations on the interactions of Schwann cells and astrocytes following X-irradiation of neonatal rat spinal cord. Myelination was inhibited in the spinal cord of three day-old rats with 2000 rads of X-irradiation. Myelination subsequently occurred as a result of caudal migration of oligodendrocytes and extensive invasion of the cord by Schwann cells. Although oligodendrocytes were present in areas containing Schwann cells, astrocytes were absent. The presence of Schwann cells in the neuropil of the spinal cord did not stimulate production of basement membrane by astrocytes, so no new glial limiting membrane was formed. Evidence is presented which suggests that if astrocytes do not form a glial limiting membrane when opposed by large numbers of Schwann cells they are destroyed by the invading cells. It is suggested that the glial limiting membrane normally inhibits entry of Schwann cells into the central nervous system; if this is destroyed and not reconstituted, Schwann cells can migrate freely into the neuropil.


Morphological correlates of electrotonic coupling in the magnocellular mesencephalic nucleus of the weakly electric fish Gymnotus carapo. The magnocellular mesencephalic nucleus (MMN) of Gymnotus carapo was studied by electron microscopy. This particular nucleus, characteristic of weakly electric fish, contains two principal classes of neuron. (1) Large neurons (25-35 mum): these are rounded unipolar cells, with the perikaryon partially covered by a sheath of compact myelin. The axon leaves the neuron as a short thick unmyelinated process not resembling the initial segment of multipolar neurons. The axon branches profusely and becomes myelinated very close to its origin. The perikaryal surface not covered by the myelin sheath receives abundant club endings. The synaptic interface between club endings and large neurons is characterized by alternating gap junctions and attachment plaques. In addition, at the periphery of the club endings, "active" zones are generally present, and this synapse is therefore a "mixed" synapse. (2) Small neurons (5-12 mum): these are uni- or bipolar cells, scattered throughout the nucleus, and occasionally, grouped in small clusters. Gap junctions were not observed between neuronal perikarya in such clusters. The synaptic investment of small neurons is formed by long cup endings which almost completely encircle the perikarya. The synaptic interface between cup endings and the perikarya of small neurons is characterized by large areas of gap junctions. A single cup ending establishing gap junctions with two small neurons within the plane of the section was frequently observed and this arrangement provides a morphological basis for electrotonic coupling between small neurons by way of presynaptic fibres. In the neuropil of the MMN, there are abundant synaptic islands constituted by a large axon terminal in synaptic contact with small unidentified profiles; both synaptic elements are surrounded by numerous thin glial lamellae. At the synaptic interface, in the islands, both gap junctions and "active" zones are present. The synaptic islands must also be considered as "mixed" synapses. The morphological results presented here correlate with electrophysiological data (Szabo et al., 1975). The very short delay (0.8-1.3 ms) of the MMS response to the fish's own electric organ discharge can only be explained by the existence of electrotonic transmission along the neuronal chain of the electrosensory pathway. The presence of gap junctions between club endings and large neurons provides a morphological basis for electrotonic transmission at the mesencephalic level of the electrosensory pathway.


Functional characteristics of superior olivary neurons to binaural stimuli. This investigation was undertaken to study the timing properties of low-frequency binaural neurons located in the medulla of kangaroo rat (Dipodomys spectabilis). The results show that the response variables, vector strength (VS) and discharge rate (DR), are not necessarily related responses; each may be conveying a different parameter of acoustic stimuli. The results also lead to the conclusion that binaural low-frequency neurons, whether they are excitatory-excitatory (EE) or excitatory-inhibitory (EI), in essence, function similarly. Finally, this investigation presents findings which suggest that a clock, which may be part of a mechanism for pitch as well as for spatial localization, is activated by sounds, providing thereby a reference signal for neural discharges.


Effects of early binocular deprivation on visual input to cat superior colliculus. 1. Recent work has demonstrated at least three distinct inputs to the superior colliculus in normal cats: a) the W-direct retinotectal pathway; b) the Y-direct retinotectal pathway; and c) the Y-indirect pathway which involves Y-cells in retina and lateral geniculate nucleus plus complex cells in cortex, the last being the corticotectal cells. 2. We investigated these inputs in five cats raised with binocular eyelid closure by studying the electrophysiological properties of 164 collicular neurons. After such binocular deprivation, the Y-indirect pathway was missing and the Y-direct pathway appeared reduced, although the W-direct input seemed unaffected. 3. Despite the loss of the Y-indirect input, collicular activation to electrical stimulation of cortex seemed normal in these cats. This suggested that the Y-indirect loop was affected between the optic tract and cortex, and this, in turn, correlated to the previously described reduction in recordable Y-cells from the lateral geniculate nucleus of binocularly deprived cats. 4. We found receptive-field correlates to this loss of Y-direct and Y-indirect input in the binocularly deprived cats. Compared to collicular neurons in normal cats, those in deprived cats exhibited abnormally strong dominance by the contralateral eye, loss of directional selectivity, and loss of responsiveness to fast visual stimuli. 5. These and other data lead to the suggestion that in normal and monocularly deprived cats, the corticotectal input dominates collicular receptive-field properties, whereas in binocularly deprived cats, the remaining retinotectal input dominates these properties.