Abstract
In chloralose-anesthetized, immobilized cats, evoked responses in the superior colliculus by the electrical stimulation of the ipsilateral cortex were studied. Systematic electrical stimulation of the hemisphere by the silver ball bipolar electrodes evoked negative-positive or positive field potentials in the stratum opticum of the superior colliculus. The effective sites on the cerebral cortex were found to be the posterior sigmoid, dorsal part of the coronal, the anterior part of the anterior suprasylvian gyri (somatosensory areas) as well as other sensory cortices (acoustic and visual areas). Electrical stimulation of the somatosensory cortex elicited field potentials in the ipsilateral superior colliculus which showed a constant sequence of wave form and amplitude. They increased in amplitude, reached a maximum and then decreased as the electrode was advanced deeper into this organ. The depth at which a maximal response was recorded was in the stratum album intermediale. This was confirmed by the histological examination with the electrolytic lesion technique. These results were compared with those reported in our previous paper (Tamai and Ogawa 1972).
