[Specificity of the effect of a super high frequency pulse-modulated electromagnetic field on evoked potentials of the cat visual, auditory,and sensomotor cortex upon stimulation with light and sound]. / Spetsifichnost' vliianiia sverkhvysokochastotnogo impul'sno-modulirovannogo élektromagnitnogo polia na vyzvannye potentsialy zritel'noi, slukhovoi i sensomotornoi kory mozga koshki pri stimuliatsii svetom i zvukom.

Effects of a pulsed-modulated superhigh frequency field (950 MHz, peak power of 300 mkW/cm2 and 1.5 mW/cm2, pulse duration of 1 ms, single pulse irradiation mode, a pause between an electromagnetic pulse and an optic or auditory stimulus--20 ms) on the cat's brain evoked potentials were investigated in the optic, auditory and sensomotor cortex using acoustic and visual stimulation. It was established that during an exposure to electromagnetic waves with peak power of 300 mkW/cm2 there were no reliable changes of the amplitude characteristics; but the amplitude of the auditory evoked potentials was reliably higher and the amplitude of the optic evoked potentials was reliably lower when they were affected by an electromagnetic field with peak power of 1.5 mW/cm2.

Interhemispheric asymmetry of homotopic transcallosal responses of the auditory cortex in the cat.

In acute experiments on 29 d-tubocurarine immobilized cats, with topographical pick-up of potentials from 150-170 symmetrical points of the auditory cortex, the interhemispheric asymmetry of homotopic transcallosal responses were studied. It was established that in the majority of the animals the potentials in the right hemisphere had a greater amplitude and shorter latent periods as compared with the responses of the left hemisphere. A dependence of the properties of the interhemispheric asymmetry on the sex of the animal was noted. In females the asymmetry was characterized by a right hemispheric tendency and by a greater magnitude as compared with males. The maximal magnitude of the asymmetry was detected in the group of pregnant females. The hypothesis is proposed to the effect that the established polarity of transcallosal influenced in the auditory cortex is associated with the dominance of the right hemisphere in the organization of spatial audition.

Functional organization of the callosal connections of the cat auditory cortex.

In acute experiments on immobilized cats, using a method of topographical recording of homotopic and heterotopic transcallosal responses, the functional organization of the callosal connections of the auditory cortex was investigated. It was established that the homotopic potentials of the primary projection field (AI) have the greatest amplitude, minimal temporal parameters, and the maximal stability of these characteristics as compared with the associative fields of the auditory cortex (AII, AIV, Ep). The heterotropic transcallosal responses in field AI appeared during stimulation of the analogous field, while in field Ep, they were recorded both during stimulation of the analogous field, and of fields AI and AII of the opposite hemisphere. It is hypothesized that the structure of the transcallosal connections of the primary projection field s of the auditory cortex is characterizised by homotopy, whereas in the associative auditory fields the role of heterotopic transcallosal interactions increases. It is possible that such a structure of the transcallosal connections assures a significant role for interhemispheric interactins in the mechanisms of spatial audition.

[Interhemispheric asymmetry of homotopic transcallosal responses of the auditory cortex in the cat]. / Mezhpolusharnaia asimmetriia gomotopicheskikh transkallozal'nykh otvetov slukhovoi kory koshki.

In majority of 29 immobilized cats under study, the potentials in the right hemisphere had a greater amplitude and shorter latencies than in the left hemisphere when comparing 150-170 symmetrical points in the auditory cortex. The interhemispheric asymmetry depended on the sex of the animals: it was more obvious in females. The maximal asymmetry was observed in pregnant females. The described polarity of transcallosal influences in the auditory cortex seems to be associated with the predominant role of the right hemisphere in organization of spatial hearing.

[Functional organization of the callosal connections in the auditory cortex of the cat]. / O funktsional'moi organizatsii kallozal'nykh sviazei slukhovoi kory koshki.

Homotopic transcallosal potentials of the cat auditory cortex primary projection area (AI) had the greatest amplitude, the minimal temporal parameters and the maximal stability of characteristics as compared with the responses of the auditory cortex associative fields AII, AIV, Ep. Heterotopic transcallosal responses in the AI field occurred in stimulation of the field under the same name whereas in the Ep field the responses occurred both in stimulation of the same and the AI and AII fields of the opposite hemisphere. The structure of transcallosal connections of the auditory cortex primary projection field seems to be characterized by homotopy whereas in associative fields the role of heterotopic transcallosal interactions seems to increase. Such a structure of transcallosal connections seems to maintain the important role of interhemispheric interaction in mechanisms of spatial hearing.