Field potential and single unit analyses of the avian dorsal motor nucleus of the vagus and criteria for identifying vagal cardiac cells of origin

The compound action potential components and their associated fiber contingents were investigated in the pigeon vagus nerve with a view toward identifying the vagal cardioinhibitory fibers. In the cervical vagus, the compound action potential evoked by electrical stimulation included four major components that conducted at 17.0-30.0 (A-wave), 8.0-14.5 (B2-wave) and 0.8-2.0 (C-wave) m/sec. Cardiac slowing was not elicited until activation of the Bl-wave, and the bradycardic response was maximal when this component was maximized. Electron microscopic analysis of the cervical vagus revealed myelinated fibers 1.1-6.8 micron in diameter and unmyelinated fibers 0.3-1.4 micron in diameter. A contingent of myelinated fibers approximately 2-4 micron in diameter apparently generated the Bl-wave, while the prominent unmyelinated fiber contingent (37%) accounted for the C-wave. Analysis of various vagal branches indicated that approximatley 20% of the cervical vagal fibers exit the main trunk between cervical and mid-thoracic levels, but few of these are the larger myelinated fibers greater than 2 micron in diameter. The upper abdominal vagus consists largely of unmyelinated and small myelinated fibers, and consequently the vast majority of larger myelinated fibers found in the cervical vagus exit between mid-thoracic and upper abdominal levels, presumably in the cardiac branches. Direct examination of the cardiac branches confirmed this. Thus, it is concluded that the Bl-wave of the compound action potential is uniquely associated with cardiac slowing, that this component is generated by myelinated fibers ranging from 2 to 4 micron in diameter, and that almost all such fibers are destined for the cardiac branches of the vagus.     

Field potential and single unit analyses of the avian dorsal motor nucleus of the vagus and citeria for identifying vagal cardiac cells of origin

Field potentials evoked by mid-cervical vagal stimulation were systematically mapped in the dorsal motor and solitary nuclei of the pigeon. Since responses varied predictably with microelectrode position, they could be used for localization in the dorsal medulla. By varying stimulus intensity and monitoring the vagal compound action potential, contributions of the different compound action potential waves were then established. Activation of the Bl-wave, which includes cardioinhibitory fiber activity, has its most prominent effect in the intermediate rostrocaudal zone of the dorsal motor nucleus in the region of subnuxleus b. This is where the cells of origin of the vagal cardiac fibers have previously been anatomically localized. Single unit experiments then established that (a) vagal motoneurons with axonal conduction velocities in the cardioinhibitory fiber range (8.0-14.5 m/sec) are primarily localized to the intermediate rostrocaudal zone of the dorsal motor nucleus in the region of subnucleus b, and (b) motoneurons in this zone that conduct at 8.0-14.5 m/sec distribute their axons in the cardiac branches. Furthermore, no error is introduced by identifying such neurons with mid-cervical rather than midthoracic vagal stimulation. Thus, the following criteria establish a neuron as giving rise to a vagal cardioinhibitory fiber: (a) localizing it to the intermediate rostrocaudal zone of the dorsal motor nucleus on the basis of the field potential evoked by mid-cervical vagal stimulation; (b) antidromically activating it with mid-cervical vagal stimulation; and (c) demonstrating that its axon conducts at 8.8-14.5 m/sec.     

Organized cerebral heterotopia in the ethmoid sinus: A case report

A 60-year-old woman afflicted with spontaneous CSF rhinorrhea was found to have a heterotopia consisting of well-differentiated neurons organized in layers in the lamina propria of the mucosa of the ethmoid sinus. This heterotopic cerebral anlage is best classified within the spectrum of “nasal gliomas”. The origin of this malformation is a failure of closure of the anterior neuropore which delays the ingrowth of the mesoderm that is destined to form the skull and dura beyond the 10th week of gestation, leaving behind trapped cerebral tissue. The presentation of this congenital malformation late in life is attributed to the development of sinusitis.     

Retinal afferents to the pigeon optic tectum: discharge characteristics in response to whole field illumination.

Responses of pigeon retinotectal afferents to changes in whole field illumination are quantitatively analyzed for 313 units recorded in the stratum opticum. One hundred per cent of these units were responsive in unanesthetized birds and 92.9 percent in urethane anesthetized preparations. Of the responsive units, 92.4 percent (anesthetized) and 100 percent (unanesthetized) gave on-responses whose discharge characteristics showed an orderly relationship to stimulus intensity. Following the on-response, discharge generally ceased during sustained illumination. At stimulus termination off-responses frequently occurred, their probability being a function of stimulus intensity and duration. This probability, as well as specific response characteristics, could be predicted to a large extent from on-response characteristics. Anesthesia and level of background illumination predictably affected these response characteristics quantitatively but did not alter them qualitatively. It is hypothesized that with respect to whole field illumination the pigeon's retinotectal afferents constitute a homogeneous population continuously distributed according to threshold for intensity change.     

Long-lasting depression of hippocampus-mammillary body evoked potentials following stimulation of the basal amygdala in cats

Hippocampus-mammillary body evoked potentials were recorded in awake, unrestrained cats. Electrical stimulation of the basal amygdala with intensities eliciting behavioral reactions depressed the amplitude of the evoked responses. This effect, shown in 31 experiments, lasted for 20 min up to more than 4 hr. The induction of epileptic seizures (n = 5) due to amygdaloid stimulation did not modify the duration of this depression. The effect was specific for the basal amygdala, because stimulation of central amygdala and mesencephalic reticular formation did not alter the hippocampus-mammillary body evoked potentials. Lesions within both basal and central amygdala had no constant effect on the hippocampus-mammillary body evoked potentials. The mechanism underlying the suppression of the hippocampus-mammillary body evoked potentials due to electrical stimulation of the basal amygdala is not dependent on paroxysmal activity within hippocampus and mammillary body, as was shown by depth recordings. It is speculated that this mechanism might have a protective function in the propagation of ictal discharges originating within the hippocampus.     

Mitochondrial myopathy with multisystem abnormalities and normal ocular movements.

A woman aged 27 years is described with mental retardation, short stature, epilepsy, muscle weakness, chorioretinitis, nerve deafness, ataxia, abnormalities of the electroencephalogram and electrocardiogram, elevated cerebrospinal fluid protein and abnormal carbohydrate metabolism. There was no ophthalmoplegia. Histopathological studies on quadricepts muscle biopsy demonstrated a high proportion of Type I fibres with subsarcolemmal collections of granular material (“ragged-red” fibres). There was also an increase in intracellular lipid. On electron microscopy, abnormal mitochondria containing paracystalline inclusions were seen predominantly in subsarcolemmal regions. The patient differs from other cases of mitochondrial myopathy with this syndrome in having normal ocular movements. Muscle disease in such cases appears to be only one manifestation of a more widespread disorder of tissue metabolism.     

A study of a myopathy presenting as idiopathic scoliosis: Multicore disease or mitochondrial myopathy?

Seven cases from a family with a myopathy categorized as “multicore disease” are presented. The clinical picture is unusual because of the predominant progressive involvement of the axial skeletal muscle, with scoliosis and disproportionate respiratory failure as the major clinical features. The propositus and his cousin have both suffered from scoliosis without limb weakness. There is a possibility that this myopathy may be responsible for some cases regarded as idiopathic scoliosis, especially idiopathic infantile scoliosis.The clinical picture is highly variable, and there are sub-clinical cases. The inheritance pattern is consistent with either autosomal dominant, sex-linked recessive or extra-chromosomally inherited disease.Electron microscopy revealed mitochondrial abnormalities, which may have resulted in the Z-disc pathology.     

The electroencephalogram in neglect.

The extent of electroencephalographic (EEG) abnormalities in 23 consecutive patients with unilateral neglect was compared with the extent of EEG abnormalities in 20 matched aphasic controls. In the neglect group, 22 patients showed EEG slowing that extended over the entire hemisphere. In the control group only 8 patients showed similar hemispheric slowing. This study demonstrates that patients with unilateral neglect from discrete lesions may have EEG slowing in regions of the hemisphere that are remote from the lesion. This study also provides support for the hypothesis that neglect is a unilateral arousal defect.     

Facilitated reversal learning of a spatial-memory task by medical septal injections of 6-hydroxydopamine

To assess the role of hippocampal norepinephrine in learning and memory, rats were treated with medial septal injections of 6-hydroxydopamine either prior to or after acquisition of a spatial-memory task. No effect on acquisition learning or retention was observed. However, reversal learning was significantly enhanced in all treated animals regardless of whether treatment was prior to or after acquisition. Our results do not support a role of hippocampal norepinephrine in selective attention, but rather indicate a direct involvement in memory processes.     

Sea-blue histiocytes and sural nerve in neurovisceral storage disorder with vertical ophthalmoplegia.

Ultrastructural investigation of bone marrow histiocytes in neurovisceral storage disorder associated with vertical ophthalmoplegia revealed 3 types of cytosomes: (1) lamellar cytosomes; (2) larger cytosomes composed of lamellar fragments and a granular component; and (3) large irregular cytosomes with amorphous and granular portions, often including fingerprint profiles--in some of these, lysosome-like bodies were numerous. The lamellar cytosomes corresponded to vacuoles seen by light microscopy. The Type 2 and 3 cytosomes were the ultrastructural substract of Wright-Giemsa stained blue granules. Histiocytes having a predominance of Type 2 cytosomes in a cytoplasm rich in free ribosomes had the appearance of sea-blue histiocytes at the light-microscopic level. Transformed Type 1 cytostomes served as building blocks for Type 2 and 3 cytosomes. In the sural nerve, Schwann cells and endoneurial fibroblasts accumulated autofluorescent lipopigment but no lamellar cytosomes or their fragments were found on electron-microscopic examination. Ultrastructure of sea-blue histiocytes in this disease differed from that observed in some other diseases.     

Family and community variables in adjustment of Turkish and Missouri schizophrenics

Over a period of several years, drug studies conducted at the Missouri Institute of Psychiatry and replicated in Turkey suggested that discharge problems of schizophrenic patients in both countries were severe, but diametrically opposed in nature. In Missouri, patients' families frequently were reluctant to take patients home from the hospital; when they did, there were adjustment problems many times ending with readmission; often, discharge could be made only by using community facilities such as halfway houses, nursing or boarding homes, or foster communities. By contrast, in Turkey, doctors encountered problems in keeping patients in hospital long enough for them to achieve maximum improvement; a review of their studies showed an attrition rate in some instances of almost 25%. The apparent clinical reasons given were the families' and patients' wishes for the patient to return home as soon as improvement was noted; and despite doctors' explanations that greater improvement could be achieved, patients eloped or left against medical advice if discharge was denied.     

Similar levels of immune complexes in cases of multiple sclerosis and their unaffected relatives

To investigate the possible effect of the hypothetical multiple sclerosis susceptibility (MSS) gene on circulating immune complexes, we employed a sensitive assay to test for the presence of immune complexes in sera of MS patients and unaffected relatives classified by the presence/absence of HLA-defined markers for the MSS gene. We found no significant differences between cases and relatives. The results suggest that elevated immune complex levels in MS patients' sera reported by others may not be unique to MS cases, but may represent instead a familial phenomenon. We also report a possible association between the A3 + B7 haplotype and increased immune complexes.     

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.     

In vitro cellular responsiveness in multiple sclerosis patients to a purified measles virus nuclear core and to other viral antigens

The Clausen modification of the peripheral blood buffy coat leukocyte migration test was used to test patients with multiple sclerosis, normal subjects and patients with other neurologic diseases for cell-mediated immunity to commercial measles virus, purified nuclear core material from a human neurotropic strain of measles virus, as well as to commercial preparations of rubella, mumps and parainfluenza HA₂. Leukocytes of multiple sclerosis patients showed significantly less mean inhibition of migration in the presence of both measles antigens, mumps and parainfluenza but no difference from controls when incubated with rubella. No correlation could be found between the degree of migration inhibition and concomitant serum anti-measles neutralization antibody titers to the same strain of virus. The use of purified viral antigens might result in more meaningful studies of the status of cell-mediated immunity to viral antigens in multiple sclerosis. The relationship of our findings to other studies in this area and to the pathogenesis of multiple sclerosis is discussed.     

Tablets and talking—A spurious contrast in psychiatry

Pharmacotherapy and psychotherapy of psychiatric patients are not given equal appreciation. Particularly in syndromes with marked psychogenic or psychosocial overtones, psychotherapy is regarded as the causal therapy par excellence. In these cases (the vast majority), psychotropic drugs are believed to have at best a symptomatic importance and to entail the risk of effacing the true causes. I consider this view to be as unfelicitous as it is wrong, because: (1) Psychosocially determined behavior disorders, too, have a neurochemical substrate; (2) It is by all means sensible to make an attempt to normalize behavior by correction of this substrate; (3) Normalization of the cerebral substrate with the aid of pharmacotherapy is no less a causal type of therapy than is reduction of the pathogenic input with the aid of psychotherapy; (4) This means that pharmacotherapy and psychotherapy are complementary, and that each separately is an incomplete therapy.This argument is valid where psychotropic drugs with a relatively specific effect are available, as they are for the vital depressions and psychoses of the schizophrenic type. In these groups of patients, empirical findings confirm the theoretical expectation formulated (4) above. It is postulated that, for the treatment of neuroses which has so far been based entirely on psychotherapeutic intervention, much is yet to be expected of future developments in psychopharmacology.     

Milieu therapy reexamined

Milieu has been used to mean a democratic value system, a ward management system, and an environmental treatment approach. Sullivan's dictum, although partially true, can create the impression that the environmental needs of madmen are exactly equivalent to the needs of any group of people living together.We cannot be content with the similarities between our patients and ourselves. We must investigate the meaning of schizophrenia as it relates to the interaction of a specific organism and its environment. This requires a sophisticated interactional theory, such as Piaget²² has developed in the area of cognitive development. Such a theory accounts for the nuances of the organism, as well as the nuances of the environment, in a manner that cannot be totally achieved by the sociologic and behavioral models.Two phenomenologic approaches to environmental specificity are discussed as ways of illustrating alternatives to the more global, sociologic and behavioral models. It is hoped that increasingly environmental treatment can focus on the interaction between specific needs of different types of patients and the environment in which they are treated.