Interaction between the hemispheres in split-brain cats.

Functional interactions between the two hemispheres were studied in adult split-brain cats. The aims were to assess whether monocular learning developed independently or that there were clues for interactions between the two sides of the brain during acquisition of opposite learning tasks. Experimental cats learned two visual pattern discriminations in which one pattern was positive for the right eye, whereas the other pattern was positive for the left eye. Control cats learned the same problems, but the same pattern was positive for both eyes. The open eye was changed from one session to the next in both groups of cats. In general, monocular performances of experimental cats were asymmetrical because they learned better and faster with one eye than with the other eye. Instead, no differences between the eyes were found in control cats. Statistical analysis of the data indicated that learning in experimental cats was significantly slower than learning in control cats, and that the difference between monocular performances was significantly greater for the experimental group than for the control group. The slower and asymmetrical monocular learning of experimental cats may reflect a conflict and a competition between the hemispheres for the control of learning behaviour, resulting in the dominance of one of them. Thus, some information about the stimuli must have been transmitted via the remaining interhemispheric connections. Symmetrical monocular learning of control group indicated that the competition for the control of behaviour was not present because there was no conflict between the hemispheres.