Biomedical subjects

V L Bianki

Publications and source records attributed to V L Bianki.

At least 19 recordsLinked to original sources

PubMed1994

[The intrahemispheric contrast in transcallosal responses and its interhemispheric asymmetry in animals of both sexes].

A certain dynamics of changes in intrahemisphere contrast was revealed in the process of development of the transcallosal response: in the beginning of the response the right hemisphere is more focal, then the left one and afterwards again the right hemisphere. In males, the main changes of focality are related to the left hemisphere whereas in females--to the right one. The focality of a greater value is characteristic of the males' transcallosal responses whereas the distribution of the EPs is more diffuse in females. A specifics of the contrast gradient dynamics is described for the projection and associative cortical areas. A zonal specifics of the intrahemisphere contrast was shown in animals of different sex.

Animals↗

PubMed1994

[The dynamics of interhemispheric asymmetry during the processing of a transcallosal signal].

Multiple homotopic transcallosal responses were led from the visual, temporal, auditory and motor cortical areas in Wistar rats. Temporal parameters of positive as well as negative components of the responses revealed alteration of the interhemispheric asymmetry by the rule of right-left-right shifting. By the amplitude parameters of negative components the asymmetry was right-left-right whereas by the positive oscillations amplitude it was left-right-left. The data obtained suggest a right-left-right pattern of domineering of the hemisphere cortex in processing of transcallosal signal.

Animals↗

PubMed1994

[The asymmetry of parietal-visual and parietal-auditory transcallosal potentials and their sex dimorphism].

"Reverse" transcallosal responses (TCR) occurring in the visual and auditory cortex during stimulation of the temporal associative cortex of opposite hemisphere, were studied. The right hemisphere was shown to domineer in females, whereas a greater latency of the temporal-visual positive-negative TCRs was found in the males' right hemisphere and the females' left one. These and other data obtained suggest a greater lateralisation of the brain in males.

Animals↗

PubMed1994

[The sex dimorphism in the dynamics of interhemispheric asymmetry during the processing of a transcallosal signal].

Two main patterns of interhemispheric domineering were distinguished: the right-left-right shift type and the left-right-left one. The domineering of the right hemisphere at the beginning and the end of processing of a transcallosal signal, was stronger in female rats in some areas, whereas in the majority of the areas under study domineering of the left hemisphere occurred more frequently in male rats. The data obtained suggests a greater participation of the right hemisphere cortex in females and the left hemisphere in males.

Animals↗

PubMed1993

[The role of transcallosal responses with an initial negativity in the formation of a pattern of interhemispheric asymmetry].

Negative-positive transcallosal homotopic responses (THR) occurred 2 times less frequently than the positive-negative ones in male cats, whereas the same ratio was 1:3 in female cats. The foci of maximal activity of the 1st and 2nd types THR did not coincide. The 2nd type THR were shown to have a lesser number of interzonal interconnections than in the case of the positive-negative potentials. A probable role of the negative-positive THR in limitation, contrasting of the increased excitability focus as well as the specifics of contraphasic THRs interaction in respect to the sex of animals, is discussed.

Animals↗

PubMed1992

[The effect of sex steroid hormones on interhemispheric asymmetry in rats].

The effect of gonadectomy and sex-steroid hormones treatment on functional interhemispheric asymmetry to the reaction of pain cry avoidance of another species (emotional reactions) and motor and exploratory activity of open-field behavior in Wistar rats of 3 months old has been investigated. A spreading depression technique for hemisphere inactivation has been used. The hemispheric asymmetry of the reactions in intact rats was characterized by sex dimorphism; the left hemisphere dominated to a great extent in males than in females under the control of emotional reactions; in motor and exploratory activity in open-field behavior of rats the left hemisphere dominated in males and the right one--in female. In both sexes the neonatal gonadectomy levelled the interhemispheric differences in reactions under investigation. The following treatment of females with estradiol and males with testosterone didn't restore the asymmetry. After the castration at the age of 3 months the correlation between the size and direction of interhemispheric differences became reverse. The treatment of females with testosterone and males with estradiol both castrated in adulthood restored the interhemispheric asymmetry in males and had no effect in females. The treatment of intact rats with hormones of opposite sex led to the enhancement of left hemisphere dominance in motor and exploratory activity in males and levelled the asymmetry in females. It has been shown that in adult rats sex-steroids effect predominantly the right hemisphere.

Aging↗

PubMed1992

[Sexual dimorphism in the role of the left and right hemispheres of rats in controlling pain sensitivity].

The effect of unilateral cortical spreading depression on the threshold and latency of pain vocalisation was studied in male and female Wistar rats. The effect involved a reduction of the latency both in male and female rats. However, the left inactivation latency was shorter than the right one in male rats. Thresholds were also reduced but only in male rats and for the left inactivation alone. The data obtained suggest an inter-hemisphere asymmetry in the cortical control of pain sensitivity in male Wistar rats.

Animals↗

PubMed1992

[The effect of pregnancy on transcallosal evoked potentials].

Pregnancy induced an intrahemispheric redistribution of transcallosal flows mainly in the projection areas of the cat cortex. Functional interhemispheric asymmetry (FIA) of transcallosal evoked responses (TEPs) was determined by interhemispheric distribution of negative-positive responses in non-pregnant cats, whereas in pregnant ones it was determined by the asymmetry of positive-negative TEPs. The right hemisphere played the major part in the changes of the TEPs' amplitude parameters, and the left one--in temporal parameters.

Animals↗

PubMed1991

[The pattern of the interhemispheric asymmetry of transcallosal evoked potentials in a complex study of the projection and associative cortical areas].

In 38 anesthetized cats, homotopic transcallosal responses (TCR) were studied in somatosensory, visual, auditory, sensomotor and temporal areas. The TCR were found to be functionally asymmetrical. Some specific features of the TCR asymmetry were revealed in males and females. The asymmetry was of the same direction in sensomotor and somatosensory, visual and temporal areas, whereas it was opposite in its direction in visual and auditory areas. The changes of the TCR asymmetry seem to be due to formation of a new system of functional interzonal intra- and interhemispheric connexions.

Animals↗

PubMed1991

[Sex differences in the penetrance and expressivity of interhemispheric asymmetry].

In 38 anesthetised cat of both sexes, homotopic transcallosal responses (HTR) were studied in somatosensory, visual, auditory and temporal cortex of the brain. High penetration in cases of interhemispheric asymmetry was more specific for males and found mostly in cortical projection areas. For the functional interhemispheric asymmetry of the HTR amplitude-temporal parameters a high degree of expressiveness was characteristic in female cats. Possible reasons of these phenomena are discussed.

Animals↗

PubMed1989

Interhemispheric asymmetry of positive emotional reactions in rats.

Interhemispheric asymmetry of positive conditional reactions in rats were investigated, i.e., reactions of drinking need and self-stimulation satisfaction. A successive hemisphere inactivation was performed by potassium spreading depression. Both right and left hemisphere inactivation were shown symmetrically to affect the total quantity of water consumed by the rats until complete thirst satisfaction, i.e., the need magnitude. At different stages of thirst satisfaction, however, interhemispheric asymmetry was observed: when drinking motivation was strong, the right hemisphere dominated, when it was weak the left hemisphere was dominant. Right hemisphere inactivation caused a decrease in the frequency of lateral hypothalamus self-stimulation, whereas with left hemisphere inactivation it increased, which testifies to right hemisphere dominance in self-stimulation reaction. Self-stimulation reaction was also characterized by the asymmetry of lateral hypothalamus nuclei: reactivity of the right nucleus to hemisphere inactivation (decrease or increase in self-stimulation frequency) was more pronounced than that of the left nucleus.

Animals↗

PubMed1989

Functional organization of interzonal transcallosal connections in the sensorimotor cortex.

Transcallosal evoked potentials (EP) in cat sensorimotor cortex, arising in response to stimulation of the visual or auditory zone of an opposite hemisphere, were investigated. Interzonal transcallosal responses (TCR) were shown to be present along the entire surface of the sensorimotor cortex. Videomotor EPs were mainly in the form of responses with initial negativity. The latent periods of audiomotor EPs were longer than those of videomotor EPs. Negative-positive videomotor responses had greater amplitudes as compared to the amplitudes of synphasic or audiomotor EPs. Responses with initial positivity, on the contrary, had greater amplitudes during Field AI stimulation than they had during the stimulation of Field 19. Interzonal transcallosal responses in MI zone were characterized by interhemispheric asymmetry. In a per-pair comparison of the amplitudes of response components, individual asymmetry was revealed for videomotor EPs. Audiomotor responses in the majority of investigated animals were of greater magnitude in the left hemisphere. The left hemisphere dominance for audiomotor EPs was mainly observed in females, whereas in males the asymmetry revealed was individual. It is suggested that the peculiarities of the interhemispheric asymmetry of interzonal audio- and videomotor functional transcallosal connections are determined by specificity of the intrazonal asymmetry of transcallosal streams in projection and association cortical areas.

Animals↗

PubMed1989

Interhemispheric interzonal connections in the parietal cortex.

In acute experiments on cats immobilized by tubarine transcallosal responses (TCRs) to the stimulation of the visual or auditory cortex of the opposite hemisphere were investigated in the parietal associative region. It was found that interzonal heterotopical TCRs could be recorded along the entire surface of the parietal cortex and were in two forms: positive-negative or negative-positive. Positive-negative evoked potentials (EPs) had greater latent periods. Negative-positive TCRs disappeared after the corpus callosum section or after the section of intracortical pathways on the side of recording and/or stimulation. EPs with initial positivity changed insignificantly as a result of these operations. Interzonal TCRs were characterized by the presence of interhemispheric asymmetry. The amplitude of early components in visual-parietal EPs of any configuration appeared to be greater in the right hemisphere. These responses also had a greater latent period. According to the magnitude of the late positive wave in visual-parietal TCRs the left hemisphere appeared to be dominant. Interhemispheric asymmetry in audioparietal EPs was individual. The amplitude of the early positive component prevailed as to magnitude in the right hemisphere in males and in the left hemisphere in females. The late negative wave in animals of either sex was greater in the right hemisphere. The peculiarities of generation and interhemispheric asymmetry of different components in visual-parietal and audioparietal TCRs are discussed. A symmetricising function of the parietal associative cortex is suggested.

Animals↗

PubMed1989

[The interaction of transcallosal and ascending excitation flows in the visual cortex of the cat].

The conformity of interhemispheric interaction in visual cortex were studied by means of EPs recordings in 10 immobilized cats under conditions of different time combinations of transcallosal and monocular stimulation of contra- or ipsilateral eyes. Phasic changes of the depression effects under transcallosal conditioning of facilitating effects under conditions of the model interaction similar to natural transcallosal interrelations, occurred in photostimulation of contralateral eye. Whereas the ipsilateral eye stimulation only depressed the time interaction under these conditions. The findings are discussed in terms of morphological, neurophysiological and other research data on transcallosal interhemispheric relations in the cat visual cortex. The 15-25-ms interval between heteromodal stimuli under these research conditions seem to correspond to natural conditions of transcallosal interhemispheric relations which, in binocular vision, are dynamically and topographically organized processes of excitation and inhibition.

Animals↗

PubMed1989

[Interhemispheric asymmetry of ipsilateral interzonal evoked potentials in the parietal and sensorimotor cortex of the cat].

EPs recorded in response to electrical stimulation of ipsilateral visual or auditory cortex, revealed mostly a positive-negative configuration on the surface of parietal and sensomotor cortex in 66 immobilized cats. The positive phase amplitude of the EPs was higher in the parietal area. The latency of audio-parietal and audio-motor EPs was longer than that of visual-parietal or visual-motor EPs. The distribution of the EPs over the parietal cortex revealed a mirror effect for audio-parietal responses. Interzonal EPs were asymmetrical in parietal cortex of the two hemispheres. The right hemisphere dominated, at that. Some individual interhemispheric asymmetry was also revealed between sensomotor interzonal EPs, their latency dominating in the left hemisphere for both zones. The interhemispheric asymmetry of the parietal EPs was associated to some extent with the sex of the animals.

Animals↗

PubMed1989

[Interzonal transcallosal connections of the sensomotor cortex].

Interzonal transcallosal EPs occurring in response to stimulation of visual or auditory cortex of opposite hemisphere, were recorded in the cat sensomotor cortex. Visual-motor EPs had mainly an initial positivity whereas audio-motor those were mainly initially negative. Latencies of the former EPs were longer. Negative--positive visual-motor EPs had a greater amplitude than their synphasic audio-motor ones. Initially positive EPs had a greater amplitude in stimulation of A1 rather than 19. The EPs revealed an interhemisphere asymmetry: audio-motor those were greater in the left hemisphere mainly in females. The specifics of the asymmetry seems to be due to an interzonal asymmetry of transcallosal flows of projectional and associative cortical areas.

Animals↗

PubMed1988

[Interzonal transcallosal connections of the visual and parietal cortices].

Interzonal transcallosal EPs induced by the stimulation of contralateral visual cortex were recorded all over parietal cortex and had two forms: positive-negative and negative-positive ones. The former EPs had a greater latency and peaks of phases whereas the amplitudes of similar components of contrphasic potentials did not differ much. Negative-positive EPs disappeared after section of the corpus callosum whereas positive-negative EPs practically did not change. Analogous changes of contrphasic responses occurred after section of intracortical projections on the side of recording and/or on the side of stimulation. Interzonal transcallosal responses are characterized by a functional interhemisphere asummetry. The amplitude of early components of any EPs proved to be higher and the latency longer in the right hemisphere. The left hemisphere had a larger delayed positive wave.

Animals↗

PubMed1987

Ontogenesis of transcallosal responses in cats: I. Formation of interhemispheric connections in kittens in the first month of life.

In acute experiments on kittens at the age of 1 to 30 days, anaesthesized with nembutal and immobilized with diplacine, multiple transcallosal response (TCR) recording from different cortical areas was performed. In 2-15-day kittens homotopical TCRs appeared earlier, were wider represented, and revealed a greater configuration maturity and amplitude-time parameters in associative (parietal and sensorimotor) areas as compared to projection (somatosensory, visual and auditory) zones. It has been established that interhemispheric relations in the kitten associative cortex are mediated, not only by the callosal, but also by the extracallosal system, which was evidenced by the presence of late negative components preserved after callosotomy. The results of per-layer analysis of interhemispheric responses in 1 month kittens have shown that in the parietal cortex, in the course of development, the drains of surface-positive oscillation shifted from the V to the III layer, whereas the drain of surface-negative deviation remained at the level of II-III layers. The late component was registered at the depth of layers III-IV, having a drain in the I-II layers. In the sensorimotor cortex, the surface-negative oscillation had a drain in the I-II layers, whereas the surface-positive oscillation had a drain in the II and V-VI layers. The data obtained reflect the dynamics of the formation of interhemispheric relations in the first-month-of-life kittens and testify to an increased level of their integrative interaction.

Animals↗