[Change in the functional significance of structures of the cat brain as a result of reorganization of its activity]. / Izmenenie funktsional'noi znachimosti struktur golovnogo mozga koshek kak rezul'tat reorganizatsii ego deiatel'nosti.

A study was carried out on 8 adult cats of functional role of the frontal, parietal and occipital parts of the neocortex, and also of the dorsal hippocampus, mediodorsal thalamic nucleus and caudate nucleus head, in realization of a delayed spatial choice (DSCh) before and after compensatory reorganizations of the brain activity caused by multiple electrical stimulation of the frontal part of the cerebral cortex. Compensatory reorganization led to a change of functional significance of these structures. While before this change the frontal cortex, hippocampus and mediodorsal thalamic nucleus were critically necessary brain areas for the realization of the DSCh, after it parietal and occipital cortical areas acquired such significance. The obtained data are discussed proceeding from the principle of the integrity in the brain activity.

[Systems organization of cerebral processes in the cat during learning while undergoing electrical stimulation of the neocortex]. / Sistemnaia organizatsiia protsessov mozga koshki pri obuchenii na fone élektrostimuliatsii neokorteksa.

A delayed spatial choice (DSC) was elaborated in five cats during electrical stimulation (ES) of the frontal cortical parts with a frequency of 80 imp/s. Then the task fulfillment was tested following cessation of the electrostimulation or under the action of other current frequencies (35,3 and 120 imp/s). The number of erroneous choices increased in the absence of ES or during 3 imp/s ES of the frontal parts. The effects of frequencies of 35,80 and 120 imp/s did not differ. Three cats were trained to DSC without ES. The conditioned reflexes were tested during ES of the frontal cortical parts with current frequency of 3 and 80 imp/s. Statistically significant increase of the number of erroneous responses took place in both situations. The obtained data are discussed from the point of view of the integrative activity of the cerebral structures in DSC. Its disturbance during ES of the cortical zones and dissociation (discordance) after cancellation of stimulation during which the conditioned reflex had been elaborated, point to systemic organization of brain functioning in goal-directed forms of behaviour.

[Spatio-temporal characteristics of the EEG of the cat during formation of a delayed conditioned reflex before and after lesioning the temporal neocortex]. / Prostranstvenno-vremennye kharakteristiki EEG koshki v protsesse obrazovaniia otsrochennogo uslovnogo refleksa do i posle povrezhdeniia visochnogo neokorteksa.

Regular changes in dynamics of spatial distribution of single EEG theta-oscillations was revealed in experiments on 5 cats during elaboration of a delayed conditioned reflex, before and after the ablation of the neocortical temporal zones. The data point to an important role of cortical associative areas in the processes of learning and of brain damages compensation.

[EEG correlates of the functional organization of damaged cat brain following restoration of conditioned activity]. / EEG-korreliaty funktsional'noi reorganizatsii povrezhdennogo mozga koshki posle vossstanovleniia uslovnoreflektornoi deiatel'nosti.

EEG-correlates of completed functional brain reorganization following its lesion were studied on six adult cats. Performance by the cats of a conditioned delayed food reflex restored after a bilateral ablation of the temporal cortical areas, was attended with the statistically significant changes in both temporal and spatial patterns of probability of appearance of single EEG-oscillations for all the studied frequency ranges: 2.0-4.5; 4.5-7.5; 7.5-10.5; 10.5-14.0 c/s. Reorganization of brain activity was characterized by a vast involvement of all the studied brain structures and areas: the frontal, parietal, occipital cortex, the ventral and dorsal hippocampus, the caudate nucleus head, the thalamic mediodorsal nucleus and hypothalamic lateral area.

[Space-time distribution of individual cat EEG theta-oscillations in biologically different situations]. / Prostranstvenno-vremennoe raspredelenie edinichnykh teta-kolebanii EEG koshki v biologicheski razlichnykh situatsiiakh.

A study was made of statistical properties of temporal sequences of single oscillations in theta-range arising on EEG of different areas of the cat brain in two experimental situations: indifferent to the animal or biologically significant for it. EEG of eight structures in the left hemisphere were analysed in six cats: the caudate nucleus, the ventral and dorsal hippocampus, the mediodorsal nucleus of the thalamus, the lateral hypothalamus, the occipital, temporal and frontal cortical areas. It was found that the acquisition of biological significance by the acoustic stimulus is reflected in the distribution of single EEG-oscillations of the theta-range in the studied brain structures both directly before the acoustic stimulus (background) and in the process of the animal's performance of the experimental task. The temporal distribution of the above oscillations in each brain area separately also undergoes changes.

[Effect of successive electric stimulation of different brain regions on delayed spatial choice in monkeys]. / Vliianie poseldovatel'noi élektrostimuliatsii razlichnykh oblastei mozga na otsrochennyi prostranstvennyi vybor u obez'ian.

The effect of paired successive electrical stimulation of the prefrontal cortex, hippocampus, caudate nucleus head and mediodorsal nucleus of thalamus on the delayed spatial choice was studied in two rhesus monkeys. During the first second of delay one structure was stimulated, during its last second--another one. It was found that some combinations of paired successive stimulation interfere with the precision of solving the experimental problem by animals. The obtained results are discussed with regard to the complex temporal dynamics of brain structures interactions during short-term memorizing.

[Interaction between the prefrontal cortex and hippocampus of monkeys in delayed spatial choice]. / Vzaimodeistvie prefrontal'noi kory i gippokampa obez'ian pri otsrochennom prostranstvennom vybore.

Interaction between bioelectrical processes in the prefrontal cortex and the hippocampus was investigated on three Macaca mulatta performing a task of delayed spatial choice. It was found that the processes of short-term spatial memory are reflected in certain patterns of reciprocal correlations between EEG of the given structures. Different patterns correspond to tasks of different nature. The data obtained corroborate the hypothesis that the functional significance of brain structures may change instantaneously in the course of mnestic activity, depending on regulation requirements.

[Ability of monkeys to predict the direction of a movement]. / O sposobnosti obez'ian k prognozirovaniiu napravleniia dvizheniia.

The capacity of chimpanzees and baboons for extrapolating the rectalinear direction of the movement of food was studied by means of a specially evolved method. It was found that the chimpanzees have greater extrapolation capacities than baboons both in the case of immediate and delayed decision. The factors which determine the effectiveness of extrapolation are as follows: relation between the lengths of visible and invisible sections of the trajectory, as well as the angle of trajectory deflection from the vertical line. The longer the visible trajectory section, and the smaller the deflection angle, the easier the extrapolation problem.

[The effect of electrostimulation of the premotor cortex and hippocampus on delayed choice in monkeys]. / Vliianie élektrostimuliatsii premotornoi kory i gippokampa na otsrochennyi vybor u obez'ian

The influence of electrical stimulation of the prefrontal cortex and the hippocampus on solving the problem of delayed spatial choice was studied on four rhesus macaques. Stimulation was carried out by rectangular pulses of different amplitude in the first and last two seconds of delay (lasting from five to six seconds). A statistically significant increase of errors was found during the stimulation: 1) of the structures of the left hemisphere (the effect was averaged in relation to the moment of stimulations); 2) during the first two seconds of delay (the effect was averaged as related to the structures of stimuli); 3) of the hippocampus at the beginning of the delay, and of the prefrontal cortex, at its end. The data obtained point to the dynamic nature of the functional significance of the studied brain structures in the organization of a mnestic process.