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V F Fokin

Publications and source records attributed to V F Fokin.

46 records · Page 3Linked to original sources

[Functional assymmetry of the cerebral cortex in cats during formation of a conditioned reflex].

During elaboration of a symmetric active defensive reflex, the animal is given the opportunity to make instrumental movements with the right or left paw. On the first day of elaboration, the cats can be subdivided into three approximately equal groups: with the right preferred paw, with the left preferred paw and ambidexters. After stabilization of the reflex, motor asymmetry increases in both preferred groups, while the number of ambidexters diminishes. Unilateral electric shock producing seizures, which is applied to the "dominant" or "subdominant" hemisphere, exerts correspondingly differing influences on the subsequent reproduction of the reflex. Suppression of reproduction is more pronounced when the shock is applied to the "dominant" hemisphere. The result of repetitive application of electroshock to one and the same hemisphere is that the functions of the "dominant" hemisphere are effected by the hemisphere which was not subjected to direct electrical stimulation.

Animals↗

[Participation of subcortical formations in regulating motor asymmetry in the cat during elaboration of an instrumental active defensive reflex].

Parameters of motor asymmetry and the process of learning were studied in cats during elaboration of an active defensive reflex, following unilateral coagulation of various subcortical formations, predominantly of the extrapyramidal system. The changes of these parameters developed after the coagulation independently of each other. Lesion of the globus pallidus was attended, as a rule, with non-reversible changes of motor asymmetry and slight changes of the learning parameter. Destruction of the putamen and claustrum produced temporary disturbances of lateralization and learning processes. At early stages of the instrumental habit elaboration, the destruction of pathways passing in the internal capsule from different cortical structures to formations of the extrapyramidal system, brings about changes in the parameters of motor asymmetry and the learning process; at final stages--a similar lesion does not affect either parameter.

Animals↗

[Trace elements in the neurophysiological mechanisms of the development of interhemispheric asymmetry].

The content of microelements in the cerebral cortex of rats featuring motor asymmetry was studied by the method of emission spectral analysis with inductively bound argon plasma. The content of microelements (Cd, Co, Cu, Fe, Mn, Mo, P, S, and Zn) differs reliably in the subdominant and dominant hemispheres. We propose that interhemispheric asymmetry of the content of microelements plays the key role in formation of the brain functional asymmetry.

Animals↗

[The interrelation of the level of the brain DC potential and visual evoked potentials during human aging: the norm and Alzheimer's disease].

Correlation between DC-potential level and visual evoked potentials (VEP) was investigated in normal subjects of the middle and old age and the patients with Alzheimer's disease. Significant correlation between the DC-potential level and the amplitudes and latencies of different components of VEP was found. The correlation was intensified during ageing mostly in patients. More stable positive correlation existed between local DC-potential level recorded in the occipital area of the head and the amplitude of the components N1 and P2 of VEP.

Adult↗

[Dynamics of elaboration of an active defensive reflex after combined section of the visual tract and different commissural systems].

Elaboration of an active defensive reflex (ADR) was studied on intact animals (I) and on cats after a combined section of the optic tract and the commissural systems of the midbrain (II) and after a combined section of the optic tract and the commissural systems of the telencephalon and the diencephalon (III). On the first days of elaboration, the correlation between active and passive defensive reactions changed in the animals of the III group as compared with the intact cats. The greatest difference in ADR elaboration between the intact animals and cats of the II and III groups was observed on the first day. On the subsequent days of elaboration the differences diminish and by the 4th to 6th day do not exceed the variations in the intact animals behaviour. The operated animals on the whole achieve higher parameters in differentiation training than the intact ones. In the course of ADR elaboration, against the background of a flickering light, a driving response is recorded in the visual cortical areas of all the groups during the achievement of the active defensive conditioned reaction.

Animals↗

[The neurophysiological and biochemical mechanisms of the dose-dependent amphetamine modulation of the sensorimotor cortex neurons in developing animals].

The resulting data give evidences, that after injection of the low doses of amphetamine the decrease of amplitudes both negative (NC-3), and positive components (PC-3) of the thalamo-cortical responses (TCR) of the sensorimotor cortex (SMC) takes place in 2nd-3d-weeks-old rabbits of their postnatal life. At the same time the amplitudes of these phases in 45-50-days-old animals change to greatly less extent, without any system, with low level of statistical significance. After injection of medium doses of amphetamine in 2nd-3d-weeks-old rabbits, the increase in amplitudes of both components of TCR SMC in observed, at the same time in definitive animals the amplitudes of these responses decrease greatly. After injection of the high doses of amphetamine in 2nd-3d-weeks-old rabbits the further increase in amplitude PC-3 and NC-3 is displayed, at the same time the growth of amplitude parameters of TCR SMC appears for elder animals under this concentration of amphetamine only. Neurophysiological and neurochemical analyses of these phenomena are developed. Neuro-ontogenesis hypothesis of causes of high vulnerability of the nervous system in young animals and children during critical period of increased risk under the exposure to both psychotropic drugs and endogenous psychopathogenic factors being proposed, that can simplify search for adequate psychopharmacology protector, etc.

Aging↗