Desynchronous (low voltage fast activity), synchronous (high voltage slow waves) as well as convulsive brain activities were stimulated by a computer model of neuronal population. Network excitatory and inhibitory elements possessed fundamental dynamic properties of real neurones. Being independent both of the excitability of elements and of external influence efficacy, synchronous (desynchronous) network activity resulted from the increase (decrease) of the average power of "neuronal" interconnections which imitated mutual and recurrent excitation and inhibition. The inhibition efficacy being reduced as compared with excitation, synchronization of elements became intensified. As a consequence, the rhythmic activity amplitude increased and the appearance of self-sustained oscillations simulating convulsive activity was facilitated. The probable mechanism of EEG activation by virtue of the reduction of mutual and recurrent excitation and inhibition efficacy as well as the significance of inhibitory mechanism deficiency for epileptogenesis are discussed.

Brain↗

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[Study of body temperature fields in relation to excitation of the cerebral cortex in the rat].

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Acetates↗

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[Conditioned reflex switching-over in the rat after temporary functional decortication].

Conditioned switching-over was elaborated in white rats: in one situation an alimentary instrumental reflex to sound was elaborated, in another one--an electro-defensive avoidance reflex to the same sound, different time of the day and different chamber illumination used as the switching-over factor. One-time influence of spreading depression by means of bilateral application of 10% KCl solution for 1.5 min to dura mater brought to the disturbance of the conditioned switching-over for 2-3 days. Electrolytic destruction of posterior hypothalamus area was produced in some animals. After restoration of functions one-time application of spreading depression elicited deep and long-term disturbance of conditioned switching-over. Apparently more complex conditioned activity suffers greater at short-term elimination of cerebral cortex functions, especially in conditions of compensatory recovery after lesions of the central nervous system.

Animals↗

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[The effect of neural transplantation on audiogenic seizures in rats of different genetic strains].

The effects of neurotransplantation on development of audiogenic seizures (AS) were studied in Krushinskiĭ-Molodkina (KM) rats genetically predisposed to AS and in Wistar rats especially selected for AS. Within 24 weeks after bilateral combined transplantation of the newborn striatum and cerebellum into the parietal cortex, the AS didn't develop in Wistar rats in 74% of tests. In control Wistar rats with cortical grafts or saline injections into the parietal cortex there were no significant changes in the AS development. In the experimental KM rats the grafting led to the 4-5-times increase in the AS latency. In 50% of rats it decreased the AS severity by 1-2. In the control KM rats these parameters didn't change. It was concluded that it was possible to suppress or decrease the AS development by the transplantation of the newborn striatal and cerebellar tissue into the cortex of rats predisposed to this kind of seizures.

Acoustic Stimulation↗

PubMedDate not supplied

[The mapping of spike-wave discharges in WAG/Rij rats (a genetic strain of absence epilepsy)].

The electrical activity of different cortical areas was recorded in 37 WAG/Rij rats under conditions of chronic experiment. The typical for absence epilepsy spike-wave discharges occur in EEG of all the animals of the strain. The average amplitude distribution maps were constructed based on the recording of two main components of the spike-wave discharge. The most frequently occurring discharges of 5-9 s in duration were taken for map construction. Separate maps were constructed for the beginning and for the end a discharge. It was shown that at the beginning of a discharge the maximum of spike amplitude was localized in the frontal cortical area in the site of localization of the eye, vibrissa and chewing movement centers. At the same time, the wave was better pronounced in the occipital cortical areas. At the end of a discharge spike amplitude diminished and the cortical square over which it was manifested was cut down. On the contrary, at the end of a discharge were amplitude increased and the area of its distinct recording spread to the frontal cortical areas. The wave amplitude maximum was observed over the cortical areas 17. The obtained evidence suggest the relatively independent spatio-temporal dynamics of the two main components of the spike-wave discharge complex.

Action Potentials↗