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Biomedical subjects

E N Tsykalov

Publications and source records attributed to E N Tsykalov.

16 recordsLinked to original sources
PubMed1989

[Rapid thermal waves propagated through the cerebral cortex during visual stimulation].

Fast thermowaves spreading over the brain cortex were found and investigated in acute experiments on white rats using a new method of neuroimaging: thermoencephaloscopy (TES) through the intact skull. Thermowaves (amplitude 0.005-0.1 degree C, path 2-56 mm, length 10-15 mm, duration 1.2-11.4s, speed 1-33 mm/s) were evoked by light stimulation. With a high probability (0.92) they appeared during 15s before and 26s after the rhythmical flashes (interval 1.5-3 min). In about a half of cases the wave appeared in the contralateral visual cortex (fields 17 and 18a), spread to the middle-line of the brain and to the ipsilateral hemisphere (fields 17, 18a and 7). Local circle-spreading waves in the contralateral visual cortex and other waves differing in their trajectories and spreading from the ipsilateral visual cortex were also revealed. The possible functional significance of the effect as a reflection of scanning of the cortex by the focus of selective visual attention is discussed.

Animals↗
PubMed1987

[Temperature distribution on the surface of the rat brain during direct electric stimulation].

Dynamics of spatial temperature distribution over the dorsal surface of the cerebral cortex was studied through the skull with the thermovision technique on immobilized white rats. Direct cortical stimulation revealed local thermoresponses (up to +0.2 degrees C) under electrodes, in the symmetrical point in the opposite hemisphere as well as in some other cortical zones. The response latency was within the limit of 160 ms, peak latency--2-5 s and relaxation time 2-3 min. Nembutal caused depression of thermoresponses, increase in their thresholds, limitation in size as well as slowing down of the development and prolongation in time.

Animals↗
PubMed1986

[Parameters of photic stimulation and characteristics of thermoreactions in the cerebral cortex of the white rat].

The dynamics of local thermoresponses in the brain cortex was studied through the unopened scull under patterned light stimulation of the retina in acute experiments on white rats by means of thermovision and digital image processing technique. The dependence of the amplitude, temporal and spatial characteristics of these responses on the size, retinal localization, focusing of the stimulus, its duration, number and frequency of presentation was estimated. The properties, significance and mechanisms of the revealed thermoeffects are discussed.

Animals↗
PubMed1986

[Movement of temperature waves across the cerebral cortex of the white rat].

In acute experiments on immobilized or anesthetized white rats the spatial distribution and dynamics of temperature on the dorsal surface of the cerebral cortex were investigated by the thermovision technique and digital image processing through the intact skull. Under certain conditions the appearance of moving thermowaves that spread over the cortex for 8-30 mm during 2-9 s with a rate of 2-10 mm/s was found. Among the trajectories of these waves the circular one was more common: it began in one hemisphere, spread in one or another direction, then went over to the second hemisphere, moved in the opposite direction and came back to the initial zone. Linear and semicircular trajectories were found as well with or without crossing from one hemisphere to the other. The mechanisms and possible functional significance of the effect are discussed.

Animals↗
PubMedDate not supplied

Temperature reactions of the rat cerebral cortex and distant effects of an experimentally induced excitatory focus.

The method of dynamic thermovision was used in white rats to investigate the distant reactions of the cerebral cortex arising during local chemical perturbation (2% KC1). In addition to the earlier-described temperature wave of propagating depression (T waves), local areas of warming (by 0.2-0.3 degrees) symmetrical to the site of stimulation were found in the opposite hemisphere. Latent excitation foci during local chemical action were found on the dynamic thermal maps of the brain surface in regions remote from the stimulation site in the same or contralateral hemisphere. A change in the site of T-wave origination and the typical sequence of its propagation through the cortex could be observed when two potassium foci were created, as well as the development of foci of prolonged temperature oscillations at the site of encounter of two T waves. On the basis of the obtained data several questions are discussed concerning the forms and mechanisms of distant effects in the CNS.

Animals↗
PubMedDate not supplied

[Temperature reactions of the cerebral cortex in the rat and the distant effect of an experimentally evoked excitatory focus].

By means of dynamic thermovision method, distant reactions of the cerebral cortex were studied in white rats appearing under local chemical action (2% KCl). Besides the previously described temperature wave SD (T-wave), in these conditions in the contralateral hemisphere local areas of warming up (0.2-0.3 degrees) were observed symmetrical with the place of stimulation. Under local chemical action, latent foci of excitation were revealed on dynamic thermal maps of the brain surface in the areas of the same or contralateral hemisphere, distant from the places of stimulation. During creation of two K+ foci a change was observed of place of T-wave appearance and of the usual order of its propagation over the cortex and also the formation of a focus of prolonged temperature fluctuations in the place of two T-waves meeting. On the basis of the obtained data a number of questions is discussed on the forms and mechanisms of distant effects in the CNS.

Analog-Digital Conversion↗
PubMedDate not supplied

[Spatial characteristics and the dynamics of the activation foci in the cortex during the elaboration of a conditioned reflex (thermographic research)].

In acute experiments on immobilized white rats, by thermovision methods and digital image processing, spatial distribution and dynamics of local heating and cooling of dorsal surface of the cerebral cortex was studied through intact skull during elaboration of a conditioned reflex. Distant and noninvasive thermovision methods allowed to reveal and quantitatively study local cortical thermal reactions in the somatosensory and motor cortex and in the cerebellum in the process of elaboration and testing of conditioned connection. Under discussion are mechanisms, properties and significance of these effects for investigation of learning.

Animals↗
PubMedDate not supplied

[Sensory mapping of the rat cerebral cortex by thermographic methods].

Using thermovision and digital image processing, the dynamics of thermomap in the brain cortex has been studied on albino rats through the opened skull before and during sensory stimulation. Photic, sonic and somatosensory stimuli lead to the onset of local heating foci in the corresponding cortical zones, as well as to local multiple thermoresponses in other areas. Some quantitative parameters of these effects are given and their possible mechanisms are discussed.

Acoustic Stimulation↗