Only recently has man begun to regard himself as mundane and not divine. This conceptual liberation has allowed him to ask frank questions concerning the physical and chemical mechanisms which determine or affect his behavior. Unfortunately the answers to these questions have been slow in coming. The reasons for this are two-fold: Basic ethical considerations preclude the experiments necessary to investigate the neural substrates of human behavior in man. Further, man’s behavior and nervous system are both so enormously complex and subtle, it is therefore unlikely that much real fundamental knowledge could be gained from such experiments if performed. It is more expedient to study simple behavior in simpler organisms than man to understand how nervous systems operate in general and, it is hoped, to eventually gain a better understanding of the human in particular. This tactic is known as the “model systems” approach. By discovering the strategies adopted by less complex nervous systems to deal with simple situations one can devise a realistic model of the neural mechanisms that control more complex behavior in more advanced animals.

Many animals have served as valuable sources of model systems. Among them the marine gastropod mollusc Aplysia has received considerable attention. In comparison to the human nervous system with approximately 50 billion neurons, the Aplysia nervous system contains relatively few neurons — about 20,000. Furthermore the study of the Aplysia nervous system has several other advantageous characteristics. A number of forms of behavioral plasticity that are found in all higher metazoans including man are also found in the Aplysia. These simple but non-trivial types of behavioral plasticity include habituation, sensitization and associative learning as well as easily defined qualities of neural function which we choose to call “behavioral states”. In addition the nervous system is composed of neurons which are large and, in many cases, easily identified by anatomical and physiological criteria so that the “same” cell can be studied in more than one animal under more than one set of experimental conditions. The cell bodies of the neurons in Aplysia, from which electrical recordings can be fairly easily obtained, are electrically close to their dendrites so that changes in postsynaptic potentials occurring during modifications of behavior can be monitored.

We report a case of acute neuropathy in a 46 year old female with porphyria variegata. Histologic, electron microscopic, and quantitative examinations of peripheral nerves were performed at onset of the neuropathy and at autopsy. The results revealed severe qualitative and quantitative changes in myelinated and unmyelinated fibers showing features indicative of an axonopathy with a distribution in keeping with a dying-back phenomenon.

We made an electroretinographic (ERG) and visual evoked potential (VEP) study of 12 patients with Friedreich’s ataxia whose diagnosis was established using the Quebec diagnostic criteria. ERGs and VEPs were elicited to the same stimulating conditions. Flash evoked luminance changes and pattern-specific evoked potentials to check and diamond stimuli were used. Statistical analysis of the data was made using independent sample t-tests. Significant VEP delays were present under all test conditions. The presence of significant interocular and interhemispheric delays as well as evidence of abnormal temporal dispersion of the VEP response suggest there to be both diffuse anterior visual system disease and retrochiasmal involvement in Friedreich’s ataxia. The implicit times of the ERG b-waves were statistically within normal limits but the waveforms were of low amplitude and deformed and there were significant interocular implicit time differences. These ERG results suggest there are retinal conduction abnormalities in Friedreich’s ataxia which possibly play a role in the genesis of the abnormal VEPs.

A questionnaire survey has been made of the life effects of narcolepsy in 180 patients, 60 each from North American, Asian and European populations, with 180 similarly distributed age and sex matched controls. Life-effects were attributed by the patients to the primary symptoms of excessive daytime drowsiness, sleep attacks, cataplexy, vivid hypnagogic hallucinations and sleep paralysis, and also to other frequent symptoms such as visual problems (blurring, diplopia) and memory impairment. Occupational problems were prevalent (over 75%) and included statistically significant deleterious effects upon performance, promotion, earning capacity, fear of or actual job loss and increased disability insurance. Driving was greatly affected and patients fell asleep at the wheel more frequently (66%), had near or actual accidents from drowsiness or falling asleep at the wheel (67%), and could experience cataplexy (29%) or sleep paralysis (12%) while driving. Work or home accidents attributed to sleepiness or sleep (49%) or related to smoking (49%) were much more common in patients. There were also deleterious effects on education, recreation and personality related to the disease. Narcolepsy can produce a variety of life-effects probably more serious and pervasive than, for instance, those of epilepsy, therefore emphasizing the importance of early diagnosis and treatment.

The effect of L-tryptophan, a precursor of serotonin, and placebo were studied in eight patients with spasmodic torticollis. L-Tryptophan (5gpo as a single dose) which increased free plasma tryptophan 20-53 fold improved only one out of six patients. Two out of three patients, including the subject who improved following an oral load of tryptophan, improved with L-tryptophan combined with nicotinamide, a tryptophan pyrrolase inhibitor, when administered for 1-3 weeks. However, the magnitude of clinical improvement was not impressive. Our findings suggest that impairment of serotonergic function is not a general finding in spasmodic torticollis though it may play a minor role in the manifestation of this movement disorder in some patients. The present study emphasizes some of the difficulties in evaluating therapeutic response, namely, the intrinsic variability of the disorder, the response to placébo in some subjects and the limitations of methods for measuring change.

An 8 year old boy developed cerebral abscess and purulent meningitis due to Clostridium perfringens and Clostridium paraputrificum after trauma to the left orbit. The patient made a satisfactory recovery with surgical treatment and antibiotic therapy. A review of the literature revealed that meningitis due to Clostridia is rare and usually related to penetrating trauma, and that penetrating trauma to the orbit is associated with significant central nervous system morbidity.

The natural course of the pathologic features in striated muscle was studied in a full-term infant with myotubular myopathy. At 5 days of age a muscle biopsy revealed that more than 90 percent of muscle fibers fulfilled histologic, histochemical and electron microscopic criteria of fetal myotubes. The infant died unexpectedly at 9 months of age from spontaneous rupture of a multifocal cavernous hemangioma of the liver. Postmortem examination revealed that progressive maturation of the fetal muscle had not occurred postnatally, and more than 90 percent of myofibers were still apparent myotubes. This maturational arrest was generalized to all striated muscles. The only changes detected since the neonatal period were hypertrophy of the small population of large fibers, but with minor cytoarchitectural alterations, and loss of the incomplete histochemical differentiation with ATPase stains or dedifferentiation not attributed to postmortem diffusion. Involvement of the gubernaculum testis accounted for the undescended testicles. The brain and spinal cord appeared normal. Evidence of degenerating and regenerating axons in the sciatic nerve suggested that the etiology of this maturational arrest of fetal muscle may be neurogenic.

Giant-axonal neuropathy (GAN), a chronic peripheral neuropathy with associated Central Nervous System dysfunction and tight curly hair, is described in a 17-year-old girl. Biopsies of this girl’s muscle and nerve are characteristic of this condition. Her clinical course over a 12 year period characterizes a disease of a slowly progressive nature.

A simple and reproducible injection technique has been developed for inducing an in vivo experimental astrocytoma model in rats. Newborn rats were injected with a suspension of astrocytoma C-6 cells in doses ranging from 5 to 1 X 105 cells. The optimum dose of tumor cells was found to be between 104 and 105 cells, with a consistent 100% take rate seen above 1 X 104 injected cells. The injection of less than 104 cells resulted in a decreased ability to induce tumors, and a prolonged survival. The pathology was consistent with that of a glioblastoma multiforme. The tumor showed a diffuse infiltrating border, necrosis, and pseudopalisading. Light microscopy revealed undifferentiated tumor cells while electron microscopy demonstrated rough endoplasmic reticulum, Golgi complexes, mitochondria, and the occasional cilium and centriole. The nature of the astrocytoma C-6 cell line, and the advantages, disadvantages and possible uses of the model are discussed.