Search

In conditions of tachistoscopic presentation of visual stimuli, healthy (male and female) right-handed subjects carried out a paired comparison of the stimuli presented unilaterally and in the center of the visual field. In case of recognition of images of words and objects, the number of correct answers and motor reaction time usually did not significantly differ at two interstimuli intervals (1 and 10 s). In comparing images of faces, there also were no differences by the number of reactions, and the reaction time was less at the intervals of 1 s. The left hemisphere dominated at the identification of words and female faces, the right one--at the recognition of male faces. When the right visual field was stimulated images of various classes were recognized more differentially than at the stimulation of the left visual field. The male subjects had more prominent interhemispheric differences than the females. The increase of the interstimuli interval from 1 to 10 s brought to a weakening of the functional interhemispheric asymmetry and decreasing of the differences between the male and female subjects. The obtained data show that in the processes connected with short-time memory, functional interhemispheric asymmetry is basically formed at the initial stages of the information processing.

Motor alimentary conditioned reflex was elaborated in Wistar line rats to presentation of various pairs of figures, those of larger area serving as positive signals. In tests on animals with intact brain and with unilateral hemispheric cortical inactivation, new pairs of figures were used besides basic stimuli. The level of analysis in testing experiment was lower than normal: by 5.6% at intact brain, by 16.4%--at right hemisphere inactivation, by 36.4%--at left hemisphere inactivation. Elimination of the left hemisphere produced prolongation of the conditioned reaction time, signs of frustration and aftereffect. In conditions of right hemisphere inactivation the level of discrimination of figures depended on their specific properties and the side of presentation. Conclusion is made on dominating role of the left hemisphere in analysis of abstract and concrete characteristics of visual stimuli, in control of temporal, spatial and emotional characteristics of reactions in situations when considerable abstraction and distinguishing of generalizing invariant sign "more-less" is necessary for elaboration of the conditioned reflex.

The behaviour of mice of BALB/c line was studied in a symmetrical multialternative Y-maze: their motor, alimentary and investigating activities as well as spatial-motor asymmetry. In animals with inactivated left hemisphere, as compared to intact ones, the motor and alimentary activities were lowered, and the investigating one augmented. Instead of the weak left-side asymmetry a distinct left-side preference appeared of most Y-maze sections, and right-side preference for approaches to the feeders. Elimination of the right hemisphere did not change the motor activity; the alimentary one decreased and the investigating one augmented, but less than during inactivation of the left hemisphere. On the whole, the right-side asymmetry appeared for all sections. According to all parameters studied, the influence of the left hemisphere on animal behaviour was more expressive and diverse. Spatial preference is formed with participation of influences of both hemispheres. The differences between them are more qualitative than quantitative.