Correlation between electrical activity in symmetrical regions of the cerebral cortex and unilateral lesions]

Functional interrelations between cerebral hemispheres, and particularly, between their symmetrical areas, were studied during compensatory processes in patients with tumours localized in one of the hemispheres. Analysis of spontaneous electrical activity before the operation on the tumour revealed several types of interhemispheric relations. The existence of a sharply pronounced pathological activity in one hemisphere, testifying to inactivation of cortical cells, is, as a rule, accompanied by activation in the intact hemisphere, especially in the areas symmetrical with those injured. In cases of less pronounced pathology, with partial retention of activity of the cortical cells in the injured areas of the affected hemisphere, a lesser degree of activation is observed in the intact hemisphere. The data point to a development of substituting-compensatory processes in the areas of the intact hemisphere symmetrical with the injured ones and to the possibility of testing the processes electrophysiologically.     

Bursting activity in visual neurons of the cat cortex during pattern detection

The time course of neuronal response to presentation of a static flashing slit at different angles and both light spots and light strips moving in different directions was investigated in the Clare-Bishop area of the cat cortex. It was found that orientational and directional tuning patterns were mainly determined by the bursting constituent of the response and could be measured according to the number of spikes per burst or the actual number of bursts. A closed-loop model for pattern detection is introduced to shed light on bursting activity.V. Kapsuko State University, Vil'nius. Translated from Neirofiziologiya, Vol. 19, No. 3, pp. 335–343, May–June, 1987.     

Spontaneous electrical activity of the rat cerebral cortex during microwave irradiation

A study was made of changes in spontaneous electrical activity of rat brain cortex induced by a single exposure to microwave radiation (electromagnetic fields of 0.1, 1.0, 10, and 35 mW/cm2). The animals were exposed in anechoic chambers to continuous waves at 2450 MHz in conditions of continuous generation. The data obtained indicate that the EEG parameters change under the effect of microwave radiation. The technique applied permits to study the occurrence and development of the CNS reactions to microwave radiation at the time of action of the factor.     

Impulse activity of neurons of the visual and somatosensory regions of the cerebral cortex at different stages of goal-directed behavior

Impulse activity of neurones of the visual and somatosensory cortical areas was studied in free moving cats during performance of conditioned instrumental food-procuring reactions to the presentation of light or sound. It was established that the units of these cortical areas may participate in both all or individual stages of complex instrumental behaviour. The visual cortex neurones are more extensively involved in the formation of successive stages of the goal-directed behavioral act. Significant differences were revealed in the unit responses of the visual and somatosensory cortical areas at the moment of the switching on of the conditioned signal, at the period of "reinforcement anticipation", at the moment of appearance of milk, the reinforcing agent, and during reinforcement, when the milk was lapped by the animal.     

Neuronal interaction in the cat cerebellar cortex: A cross correlation analysis

Neuronal interaction in the cat cerebellum was investigated by cross correlation analysis techniques. Excitatory connections of varying effectiveness were found between neurons of 13 out of 90 pairs investigated (or 14%). Inhibitory interaction was observed in 38 pairs, or 42%. Neurons of 26 pairs (40%) had shared inputs. Effectiveness of connections between cerebellar cortex neurons was demonstrated by changing stimulus parameters. Findings obtained agree with existing data on the functional organization of the cerebellar cortex. Possible reasons for the large numbers of inhibitory connections discovered are discussed.Institute of Higher Nervous Activity and Neurophysiology, Academy of Sciences of the USSR, Moscow, Institute of Experimental Biology, Polish Academy of Sciences, Warsaw. Translated from Neirofiziologiya, Vol. 19, No. 5, pp. 672–678, September–October, 1987.     

A spectral-correlational analysis of the electrical activity of the sensorimotor cortex and the internal geniculate body during a motor-polarization dominant]

By spectral-correlative analysis the dynamics was studied of structural changes of coherent relations of the electrical activity of the sensorimotor cortex and medial geniculate body (MGB) of the rabbit under motor polarization dominant created by the action of DC anode on the sensorimotor cortex area. It was shown, that in the power spectra of the MGB, besides the increase of the delta-region components in interstimulus intervals at the dominant, during the action of the sound stimulus a distinct maximum appeared in the alpha-rhythm range of the electrical activity of MGB of the "dominant" hemisphere. The coherence increase of the delta-range of the MGB and the sensorimotor cortex electrical activity in the "dominant" part of the brain was manifested exclusively in the period of sound stimulus action.     

The spectral correlation characteristics of the brain electrical activity in the rabbit during thirst]

Spectral-correlation analysis of the summate electrical activity of a number of subcortical structures of rabbit brain, having, by literature data, a relation to drinking behaviour showed that the increase of drinking excitability, induced by water deprivation was accompanied by definite reconstruction of biopotentials. In electrical activity of the studied structures, the spectrum power, as a rule, decreased (except in the paraventricular nucleus), and a definite structure of coherent connections between the subcortical and cortical potentials was established. Among the studied subcortical formations, structures (anterior hypothalamic area, lateral preoptic area, medial preoptic area, paraventricular nucleus) could be singled out where reconstructions of spectral characteristics of biopotentials took place most regularity, and the electrical processes in which were characterised by coherence index by an increase of spatial interconnection with the neocortex potentials, what allows to consider them as most significant for organization of drinking excitation.