Extracellular recording of neuronal activity of the cat heart ganglia

An analysis of results of extracellular recording of neuronal activity of the cat heart ganglia showed that neurons of the intracardiac ganglia, in contrast to the neurons of other visceral ganglia, were characterized by the absence of spontaneous electrical activity. Variations in the duration and frequency of mechanically induced spike discharge are indicative of a different degree of neuronal membrane depolarization and its stability in time after mechanical action of the tip of the recording microelectrode on the cell. The evoked electrical activity was not dependent on the rhythm of local contractions of the myocardium. Some evidence of interneuronal interaction at the ganglion level under the conditions of complete isolation of the right auricle has been presented.     

Mycoses of the central nervous system. Anatomopathological data of cryptococcosis and cerebral aspergillosis

The pathological findings of the cerebral involvement in deep-seated fungal infections in routine autopsy is reported. In 42 cases of mycotic infections studied among 3.966 autopsies, there were 8 cases of cryptococcosis and 2 of aspergillosis of the brain, showing a very low frequency of central nervous system involvement, occurring in a proportion of 1:400 autopsies. The histopathological findings of the brain in cases of cryptococcosis showed the spectrum of inflammatory reactions already described, although most of the cases presented with mild to severe meningitis with large number of giant cells, and slight degree of involvement of the nervous tissue. The cases of aspergillosis showed a pattern of severe necrotizing meningo-encephalitis with large number of fungi. The paper points out the role of the histological examination in the identification of the fungi in tissues and their morphologic reactions.     

Down-regulation of norepinephrine transporter function induced by chronic administration of desipramine linking to the alteration of sensitivity of local-anesthetics-induced convulsions and the counteraction by co-administration with local anesthetics

Alterations of norepinephrine transporter (NET) function by chronic inhibition of NET in relation to sensitization to seizures induce by cocaine and local anesthetics were studied in mice. Daily administration of desipramine, an inhibitor of the NET, for 5 days decreased [(3)H]norepinephrine uptake in the P2 fractions of hippocampus but not cortex, striatum or amygdalae. Co-administration of lidocaine, bupivacaine or tricaine with desipramine reversed this effect. Daily treatment of cocaine increased [(3)H]norepinephrine uptake into the hippocampus. Daily administration of desipramine increased the incidence of appearance of lidocaine-induced convulsions and decreased that of cocaine-induced convulsions. Co-administration of lidocaine with desipramine reversed the changes of convulsive activity of lidocaine and cocaine induced by repeated administration of desipramine. These results suggest that down-regulation of hippocampal NET induced by chronic administration of desipramine may be relevant to desipramine-induced sensitization of lidocaine convulsions. Inhibition of Na(+) channels by local anesthetics may regulate desipramine-induced down-regulation of NET function. Repeated administration of cocaine induces up-regulation of hippocampal NET function. Desipramine-induced sensitization of lidocaine seizures may have a mechanism distinct from kindling resulting from repeated administration of cocaine.     

Rearrangements of efferent activity parameters in generators of cyclic motor reactions during electric stimulation of cerebellum inputs and outputs in the cat]

Rearrangements of the activity parameters of scratching and locomotor generators conditioned by electric stimulation of the inferior olive, nucleus reticularis lateralis as well as of the fastigial nucleus and nucleus interpositus of the cerebellum were investigated on decerebrate immobilized animals. Scratching and locomotor generators were characterized by the ability to effectively rearrange the time structure of their activity in response to certain changes in phase and amplitude characteristics of signals arriving both by the mossy and climbing inputs of the cerebellum. The flexor half-centre of the locomotor generator and aiming half-centre of the scratching generator increased both the period and intensity of their activity under influence of signals arriving to the cerebellum from the inferior olive and nucleus reticularis lateralis at the first half of the working phase of these half-centres. Stimulation of the inferior olive and nucleus reticularis lateralis during the second half of the flexor and aiming phases evoked somewhat different changes in correlation of activity for half-centres of the locomotor and scratching generators. A slight shortening of the activity period of the aiming half-centre during scratching and a decrease of the activity period of the extensor half-centre during locomotion were observed. Stimulation of the structures mentioned above during the working phase of half-centres controlling limb extensor movements evoked shortening of the extensor half-centres activity period during locomotion and exerted no effect on the scratching jerk half-centre activity period during scratching. The scratching generator, unlike the locomotor generator is characterized by a significant degree of resemblance of the rearrangement of generator efferent activity parameters evoked by electric stimulation of the cerebellum nuclei and its afferent inputs. Possible mechanisms of forming the correcting influences on scratching and locomotor generators from the cerebellum during changes in phase and amplitude characteristics of its input signals are discussed.     

Choline acetyltransferase and acetylcholinesterase in muscular dystrophic mice

The activities of choline acetyltransferase (CAT) and acetylcholinesterase (AChE) were assayed in various tissues of dystrophic (dy/dy) and normal mice of Bar Harbor strain 129. The brain weights of these dystrophic mice were not significantly different from those of normal mice, but the average body weight of these dystrophic mice was only 66.8% of that of the controls. The activity of CAT (expressed as unit activity per mg of protein) was very similar in the brains of both groups of animals, but the CAT activity (per mg of protein) in the hindlimb muscles of the dystrophic mice was significantly higher than that of the controls. The patterns of AChE activity, as separated by sucrose density gradient centrifugation, were distinctly different in extracts of dystrophic and normal muscle. Compared with controls, decreased activity of the 15-S and 10-S forms of AChE, with increased activity of a 4.3-S forrn of AChE, was observed in dystrophic muscle.     

Microsurgical method of transplantation of peripheral nerves

The authors present the microsurgical technique of grafting thin cutaneous nerves at the site of peripheral nerve defect. The application of grafts in place of end-to-end suture makes possible elimination of nerve stretching at the time of suturing and at the time of rehabilitation. The use of cutaneous nerves makes possible good revascularization of grafts and their correct regeneration. The use of the microsurgical technique makes possible a good evaluation of the fascicular structure of nerve trunks, their adequate resection, and good adaptation of nerve stumps and grafts connecting the corresponding nerve fascicles. The use of the technique of nerve gluing with autologous plasma enables a stable connection of grafts and stumps to be obtained, with simultaneous elimination of foreign material (threads) from the area of connection.     

The role of the pineal gland in stress

Summary A short survey of the results of our previous research into the protective role of the pineal gland against stress is given. The neuroendocrine aspect of a chronic auditory stress and the neuroendocrine aspect of ulcer disease in man were studied. Auditory stress: hypertrophy and hyperplasia of pinealocytes, hyperplasia of the STH, FSH, LTH and TSH cells, hypertrophy of the nuclei and nucleoli of the neuroglandular cells of the supraoptic and paraventricular nuclei, pronounced hyperplasia of the cells of the reticular zone of the adrenal gland, involution of the seminal epithelium, hyperplasia of the Leydig cells. Ulcer disease: numerous glial plates, cavities and acervuli in the pineal gland, numerous granules and vacuoles in the FSH cells, large and eccentrical nuclei in the LH cells, hyperplasia of the cells of the reticular zone of the adrenal gland, presence of the seminal tubules marked by signs of involution, hyperplasia of the Leydig cells. The results obtained point to the secretion of androgens and the insufficiency of the antiandrogenic function of the pineal gland both in auditory stress and ulcer disease. The anticancerogenic effect of the pineal gland would be based on its antiandrogenic function.     

Problems in the treatment of mentally ill offenders--a problem of general psychiatry?

The special position of psychiatry among the various medical disciplines is determined not least by the phenomenon of violent behaviour of some of its patients and the possibility of coercive measures against patients. The worldwide process of deinstitutionalization since the last decades is characterized by a substantial reduction of inpatient treatment and the expansion and improvement of increasingly specialized community care offers. Yet, at the same time paradoxically we are confronted with an increasing neglect of the special care requirements of a certain group of difficult-to-place patients (mostly severely chronically ill with high rates of comorbidity). Despite different social and legal conditions this has uniformly led to an increasing shift of these patients into the forensic system which is illustrated by a comparison of international and Austrian data. Forensic psychiatry is hardly able to cope with this development because of structural and personal deficits existing and is in danger of being misused primarily as an instrument of social control. From the position of forensic psychiatry the limits of deinstitutionalization are set by the feeling of responsibility of general psychiatry for a subgroup of troublesome and difficult to treat patients.     

The recalling process dynamics of associative memory neural networks in macrodynamical approach

The results of a computer study of the continuous-time version of macrodynamical system of equations governing the recalling process of associative memory neural networks are presented. The comparative analysis of two models of associative memory network—recurrent (autoassociative) and layered (feedforward)—is given. The phase portraits of macrodynamical system at a variety of representative values of parameter , the loading ratio, are obtained and the appearance of the bifurcation of equilibrium frustration (the saddle-node bifurcation) is demonstrated. The behavior of the basins of attraction of network dynamics equilibria is studied as well.     

Simple reaction-time changes in patients with unilateral brain damage

Changes of simple visual reaction time were analysed in two groups of unilateral brain-damaged patients in order to evaluate to what extent properties of lesions, clinical parameters and experimental variables might influence speed of motor response. The results confirmed that brain damage, independent of its side, produces a retardation of speed. However, the two hemispheric groups differed in so far as volume of damage had a different bearing depending on side of lesion. In spite of such a difference the presence of a general interaction between size of damage and rate of progression of lesion was noted in both the hemispheres, reminiscent of Jackson's concept of 'lesion momentum'. Aphasia was related to a significant retardation of speed in left-hemisphere-diseased patients, although a specific effect of the disturbance of language could not be demonstrated. Experimental variables such as warned vs unwarned stimulation did not affect significantly the performance of brain-damaged patients.     

Postnatal maturation in the cochlea of the cat

At birth, the cochlea of the cat, though generally developed, is still immature. Maturation of the organ of Corti begins at the base and gradually reaches the apex. In two weeks the process is complete. The most significant morphological criteria of the epithelial maturation are the formation of the tunnel of Corti and of the space of Nuel, the lengthening of the outer hair cells and the freeing of the internal spiral sulcus. On the third day after birth, the appearance of these criteria at the level of the first coil of the lamina spiralis coincides with the general physiological awakening of the auditory systems, as testified by the recording of evoked potentials from the cerebral cortex. Since such responses can be provoked by electrical stimulation of the nerve from birth onwards, the maturation of the organ of Corti appears to be the final stage in the development of the auditory system.     

Effects of intra-accumbens dopaminergic grafts on behavioral deficits induced by 6-OHDA lesions of the nucleus accumbens or A10 dopaminergic neurons: a comparison

Local lesion of the dopaminergic (DA) terminals of the nucleus accumbens have been described to reproduce part of the behavioral deficits evoked by the lesion of the whole mesocorticolimbic DA system. The most straightforward interpretation of these results would be that the DA innervation of the nucleus accumbens is necessary for and critically involved in the normal performance of the given behaviors. However, while giving some indication as to the necessity of the integrity of this DA innervation for normal behaviors, such an approach cannot reveal whether the presence of the DA innervation of other mesocorticolimbic areas (e.g. amygdala, septum, etc.) is also required. In order to approach this question, the behavioral effects of DA grafts implanted into the nucleus accumbens of rats were evaluated following two different 6-hydroxydopamine-induced lesions: a lesion restricted to the anterior DA field (DA terminals of the nucleus accumbens and to a lesser degree the frontal cortex and anteromedial striatum) or a lesion of the whole mesocorticolimbic DA system. The latter lesion induces a disappearance of the DA innervation of the nucleus accumbens as well as the amygdala, septum, etc. Both kinds of lesions led to locomotor hypoactivity, loss of locomotor activation by amphetamine, increased locomotor stimulation to apomorphine, decrease of exploratory activity and loss of hoarding behavior. These deficits were not seen in grafted animals bearing a local lesion of the DA innervation of this structure. For some of these recoveries, however, a pharmacological stimulation of the grafted neurons was required to reveal the effect of the graft. In the case of the total lesion of the mesocorticolimbic DA system, only locomotor dysfunctions were compensated by the intra-accumbens DA implants, while the other deficits remained intact, irrespective of a stimulation of the graft. These results indicate that the re-establishment of the DA innervation of the nucleus accumbens is a sufficient condition for the compensation of locomotor deficits, irrespective of the presence of the DA terminals in more posterior limbic structures, while for deficits of more complex behaviors the simultaneous presence of posterior DA innervations is also required. This latter requirement suggests the existence of some cooperativity between the different central DA terminal areas for the normal performance of behaviors.     

Current problems of pathogenesis and surgical treatment of symptomatic temporal epilepsy

The author presents a review of literature focusing of state-of-art of surgical management of epilepsy. The second part of review discusses basic principles of selection of patients with localization-caused epilepsy for surgical treatment, preoperative examination, substantiation of resection procedures, results of treatment. Special attention is given to controversial aspects of tactics of surgical management: neurophysiological and neuroimaging signs of epileptogenic zones, determination of required resection volume, value of preoperative invasive examination and intraoperative electrocorticography. Surgical complications, especially concerning medial temporal procedures, are also described.     

Assessment of roentgenographic lucencies of the skull: a systematic approach.

A review of roentgenologic characteristics of cranial vault defects suggests these criteria as favoring benign etiology: solitariness and small size, parasagittal location, smooth edges, sclerosis of margin, peripheral vascularity, and presence of bone remnants within the lesion. The more of these criteria that are present, the greater is the likelihood of benignity. Conversely, the presence of multiple defects of large size or scores of defects of small size, ragged undermined edges, total bone penetration, lack of peripheral vascularity, of absence of marginal sclerosis is presuptive evidence of malignancy.     

Evoked activity of spinal cord neurons in the early period after cutting the sciatic nerve]

The character of evoked activity of motoneurons, interneurons and Renshaw cells of white rats in low lumbar segments of the spinal cord was studied 5 days after cutting of sciatic nerves. A trustworthy rise of the amplitude of the excited postsynaptic potential (EPSP) of motoneurons on the side of nerve cutting was found. No reliable change of the membrane potential and threshold of the action potential emergence in these motoneurones was observed. Character of evoked activity of the Renshaw cells and interneurons did not differ essentially from the same of animals with the intact nerve. Possible mechanisms taking part in rising of the EPSP amplitude after cutting of the nerve are discussed.     

Mechanisms of the formation of long-periodicity oscillations in activity in nerve nets. Nets with pre- and postsynaptic inhibition

The role of presynaptic and postsynaptic processes in formation of the long-term (hundreds of milliseconds) activity of neuronal networks was analyzed by the mathematical simulation model. The long-term activity of networks with presynaptic inhibition was discontinued due to the depolarization of the neuronal terminals that achieved its critical level and to significant suppression of the effectiveness of synaptic interaction. The long-term activity of networks with postsynaptic inhibition was discontinued because of the activation of inhibitory neurons exerting strong hyperpolarizing effects on other neurons of the networks. Synchronization of neuronal discharges was important in achievement of the critical level by terminal depolarization or inhibitory postsynaptic processes that interrupted the network activity. Properties of neuronal networks with presynaptic and postsynaptic inhibition were compared with those of uniform neuronal networks (with a positive feedback between neurons only). It is concluded that introduction of the additional negative feedback circuits in a form of presynaptic or postsynaptic inhibition contributes to improvement of reliability and accuracy of the mechanism which terminates the network activity.     

Possible pathways through which neurons of the shell of the nucleus accumbens influence the outflow of the core of the nucleus accumbens

The nucleus accumbens (Acb), a major sector of the ventral striatum, is considered to be an integral part of the striatal complex. The Acb has been shown to be composed of two subdivisions, core and shell, which are distinguishable in several aspects, suggesting that these two subdivisions play different functional roles. The aim of this study was to identify pathways of the efferents of the shell of the Acb to influence the outflow of the core of the Acb. Potential disynaptic projections of the shell to the core of the Acb were investigated in chloral hydrate-anesthetized male Sprague-Dawley rats. Following ipsilateral injections of biotinylated dextran amine (BDA) into the shell of the Acb and cholera toxin B subunit (CT-B) into the core, strong overlapping distributions of BDA-labeled terminals and CT-B-labeled neuronal cell somata were found in the medial part of the ventral tegmental area, medial part of the lateral hypothalamic area, and dorsolateral part of the basolateral amygdaloid nucleus. The significance of multiple sites of relay between the efferents of the shell and the afferents of the core of the Acb at different levels of the neuraxis may be related to the functional specificity of each relay site.     

A Neurochemical Approach to the Search for Drugs for the Treatment of Symptoms of Alzheimer’s Disease

We performed an analysis of the reciprocal influences of neurons involved in the rapid-eye-movement phase of sleep (REM sleep) under the conditions of changes in the concentrations of various neuromodulators that are characteristic of Alzheimer’s disease. Several approaches to the search for drugs for the weakening of disease symptoms have been proposed taking the results of this analysis into account. The antagonists of orexin receptors were recently suggested for the treatment of Alzheimer’s disease because the anomalously high concentration of orexin, which is specific for this pathology, results in impairment of REM sleep. However, our analysis shows that the treatment with the antagonists of orexin receptors is not appropriate because it may lead to depression of the excitation of cholinergic cells, an additional decrease in the cholinergic deficit, and aggravation of symptoms of the disease. For the same reason it is unlikely that one should apply the antagonists of histamine H1 receptors and the agonists of adenosine A1 receptors. Substances that can lead to reduced activity of orexinergic neurons may be helpful instead. These substances include melatonin and the agonists of melatonin M1 receptors. Administration of these substances should improve REM sleep because it decreases the efficacy of excitation of orexinergic and histaminergic cells. Melanin-concentrating hormone also should decrease the efficacy of excitation of orexinergic cells. Additionally, the antagonists of histamine H3 receptors may be used because they promote the increased efficacy of excitation of neurons that secrete the melanin-concentrating hormone. Experimental evidence exists that indicates the benefits of these substances for improvement of REM sleep and attenuation of cognitive impairments in Alzheimer’s disease. These drugs must be applied before nightfall and their action should not be prolonged because orexinergic cells must be active in the daytime.     

Distribution of neurotensin-immunoreactivity within baroreceptive portions of the nucleus of the tractus solitarius and the dorsal vagal nucleus of the rat

We have examined the distribution of neurotensin immunoreactivity within subnuclear regions of the nucleus of the tractus solitarius (NTS) and the dorsal motor nucleus of the vagus nerve (DVN) in the rat. In order to determine which regions of the NTS were involved in the regulation of baroreceptor reflexes, we mapped the central distribution of the aortic branch of the vagus nerve using transganglionic transport of horseradish peroxidase. Comparison of the pattern of aortic nerve innervation with that of the distribution of neurotensin-immunoreactive cells and fibers shows the dorsomedial nucleus of the NTS both to be the primary site of aortic baroreceptor termination and to contain the highest concentration of neurotensin-immunoreactive elements within the NTS. Neurotensin-immunoreactive fibers are also present in medial regions of the NTS adjacent to the area postrema where they may be involved in the modulation of vagal gastric afferents. Double-label experiments, in which, on the same tissue sections, neurotensin immunohistochemistry was combined with retrograde horseradish peroxidase labeling of DVN neurons, reveal a topographic innervation of vagal preganglionic motoneurons by neurotensin-immunoreactive fibers. The heaviest innervation is of lateral portions of the DVN and adjacent ventral portions of the NTS at the level of the obex, an area which may contain cardiac motoneurons. In this region neurotensin-immunoreactive fibers can be observed in close proximity to retrogradely labeled cells. The concentration of neurotensin elements in a region of the NTS which is involved in the control of baroreceptor reflexes provides a morphological basis for the cardiovascular effects produced by central administration of the peptide. Additional control may be exerted at the level of the motoneuron, as evidenced by apparent neurotensin fiber innervation of presumptive cardiac preganglionic neurons. Similarly, the distribution of neurotensin fibers suggests that the peptide may be acting in gastric regulatory areas of the NTS or on vagal secretomotor neurons to regulate gastric acid secretion.