[Asymmetry of intra- and interhemispheric excitatory flows]

Direct cortical, transcallosal, and extracallosal responses simultaneously recorded in the cat motor cortex revealed prevalence of the positive components of trans- and extracallosal responses and of the negative component of direct cortical potentials in the left hemisphere. The asymmetry of direct cortical and transcallosal potentials has some common features: similar types, bilateral origin, mosaic, stability. The interhemispheric influence of the dominant hemisphere upon the other one is more local and differentiated than the opposite influence. The asymmetry of extracallosal responses is more obvious than that of transcallosal ones. The interhemispheric asymmetry of the intra- and inter-hemispheric flows of excitation seems to be a component of the dominant mechanism maintaining the hemispheric predominance.