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A A Pirogov

Publications and source records attributed to A A Pirogov.

18 recordsLinked to original sources
PubMed1979

Unit activity of the prefrontal cortex during delayed alternation performance in monkey.

Unit activity in the dorsolateral regions of the prefrontal cortex (s. principalis) of the monkey was analysed by multineuronal recording technique. The sequence during delayed-response alternation included anticipatory stimulus, non-specific expectancy, conditioned cue, delay, trigger stimulus and alternation performance. Food reward completed the sequence. Unit activity in s. principalis was found to be involved in such learning processes as integration of behavioural acts into an accomplished programme and storage of traces in short-term memory. The latter can be observed in successive involvement of neuronal populations during a 10 sec delay as well as in rearrangements of unit activity, the maximum of which shifts to the latest part of the delay period. Unit activity in s. principalis reflects the level of correct response, corresponding correlates of which depend on the level of attention. The dorsolateral prefrontal cortex has structural and functional characteristics for short-term storage of external signals in its neuronal nets according to the level of attention.

Animals↗
PubMed1977

[Conditions for development of off-responses to photic stimulation among cat senso-motor neurons].

On- and off-responses to a prolonged optical stimulus (up to 1000 ms) were studied in the cat sensomotor cortex. Similarity of the minimum time of stimulation resulting in the off-response with the cycle of the functional restoration after a single flash was observed. It is suggested that IPSP arising in the cortical neurons form a basis of these time intervals. The influence of stimuli of other modalities (cutaneous) on the off-responses is shown. This influence was observed in the case when the cortical neuron produced an impulse discharge to the cutaneous stimulus.

Animals↗
PubMed1976

[Changes in the activity of the cat sensomotor cortex under heterosensory stimulation].

In immobilized cats, the sensorymotor neurons were shown, in the course of habituation to the rhythmic light stimulation (1/sec), to start responding to stimuli of other modalities (somatic) when the latter were presented during the functional recovery cycle following the light stimulation. The habituation to the light stimuli did not occur when they were followed by a somatic stimulus with 100-300 msec delay. The data obtained seem to reflect the reconstruction occurring in the functional state of the sensory system.

Animals↗
PubMed1975

[The heterosensory interaction of neurons in the cat frontal association cortex].

The interaction of various sensory inputs in the cat frontal neurons was studied in the motor cortex (MI), the area of the hind-limb contralateral representation (SI), and the area of the fore-limb contralateral representation (S'I), with the aid of heteromodal stimulation. Mutual blocks between various inputs (visual, auditory, contralateral hind-limb and fore-limb projections) were observed in MI and SI within the 100-600 msec intervals. Teleceptive inputs in the contralateral fore-limb representation did not block the somatic ones, though the latter blocked the teleceptive inputs within long intervals (3000 msec and more). The somatic input interactions manifested themselves in asymmetric blocks. The cortical type of the heterosensory block seemed to prevail in the fore-limb cortical projection, while multisynaptic blocking throughout the entire neuronal chains prevailed in the MI zone and in the cortical hind-limb projection.

Animals↗
PubMedDate not supplied

[Studies on projections of somatic afferentation in the neocortex of the hedgehog Erinaceus europaeus].

Cortical projections of the somatic system in the hedgehog cortex were studied by means of the evoked potential (EP) technique. The EPs were shown to arise at a large area of the lateral cortex, the area in question being enlarged under chloralose anaesthesia. In the focus of projection of corresponding modalities the EPs posessed the least latency. Functional differences in the EP generation system both in the focus of projection and outside it are discussed. The wide EPs spreading in the lateral cortex as well as the presence of relatively differentiated projections is supposed to depend on the afferent volley dispersion to the polysynaptic pathways at the thalamic level. Considerable overlapping of sensory projection zones in the cortex is conditioned by the latter and indicates low degree of the somatic analyser organization.

Animals↗
PubMedDate not supplied

[Participation of the frontal lobes in the integrative activity of the brain in Macaca mulatta monkeys].

Frontal lobe neuronal impulsation during complex behavioral program was investigated by means of the multineuronal recording technique. This program consisted of unspecific expectation after the anticipatory stimulus, conditioned stimulus and delay period, trigger signal and alternative selection followed by food award. Such processes as combining the external stimuli into the integrated program, preservation of short term memory traces, correct and incorrect experimental task solution are reflected in principal sulcus neuronal activity. The level of correct selection and corresponding correlates of neuronal activity changes are in direct dependence on the food motivation level. The data are discussed in connection with the development of thalamos--frontal associative brain system which participates in the behavioral program formation based on current biological motivation.

Animals↗
PubMedDate not supplied

[Heterosensory interaction in neocortical neurons of the hedgehog, Erinaceus europaeus].

Reactions of neurons in different areas have been investigated in the hedgehog cortex by means of the microelectrode technique. A wide dispersion of afferent inputs was shown over the whole neocortex, alongside with the existence of definite projection foci of appropriate modalities. In the specific projection zones the conditioning heterosensory stimulation did not influence the onset of the response of the testing specific stimulus. Blocking of responses was observed in the so-called "associative" area, irrespectively of the mode of the conditioning and testing stimulation. It is suggested that the onset of responses by the specific projection zones to other stimuli depends on the specific impulsation irradiation to the specific projection pathways. Reciprocal heterosensory blocking in the "associative" zone may indicate the existence of an integrative formation in the hedgehog thalamus, possessing its own projection to the neocortex.

Animals↗
PubMedDate not supplied

[Conditioned slow negative potential during learning motor habits of different complexity].

CSNP dynamics was studied on 13 subjects in three experimental situations: 1) In combinations of acoustic and photic stimuli without performance of movements; 2) During the pressing of the palm at the moment of the anticipated photic stimulus; 3) After preliminary switching off of the photic stimulus. In the first situation CSNP does not appear; in the second, it has a maximum amplitude at the unitial stages of movement elaboration at a definite time interval, and in the third, CSNP amplitude does not decrease during 300 stimuli combinations. The CSNP amplitude, configuration and stability depend on the degree of complexity of the motor task. It has been assumed that CSNP reflects a non-specific activation of frontal and central parts of the human brain, against the background of which integration of sensory information takes place as well as the formation of a temporal program of the subsequent motor act.

Adult↗