Ontogenesis of transcallosal responses in cats: II. Formation of interhemispheric asymmetry

Experiments were performed on 59 kittens of both sexes at the age of 1 to 30 days after birth, anaesthesized by nembutal and immobilized by diplacinum, using the technique of multiple topographical TCR recording. TCRs being recorded from symmetrical points of the right and left hemispheres, interhemispheric asymmetry of their amplitude time parameters was revealed, which arose immediately following TCR appearance. In the kittens' sensorimotor cortex TCR asymmetry was individual, whereas in the parietal cortex it was species-specific. One-hemisphere dominance in kittens possessed a partial character. During interhemispheric asymmetry formation, the callosal and the extracallosal systems participated. Asymmetry dynamism was revealed in asymmetry changing with kittens' age according to form (individual/species-specific) and magnitude (intensification/weakening up to changing its sign), and it was conditioned by differences in mechanisms of hemispheric interaction in the course of the cat's ontogenesis. The process of TCR asymmetry formation was characterized by zonal specificity. The general tendency of asymmetry development during ontogenesis in the cat was intensification, with age, of the integrative interaction of those systems which supported it.