EFFECT ON ELECTROENCEPHALOGRAM OF LESIONS OF CEREBRAL CORTEX AND BASAL GANGLIA IN MACACA MULATTA

Abstract

Lesions were made in the cerebral cortex and basal ganglia of 41 Macaca mulatta and the electroencephalograms (EEGs) recorded before and after operation. In every instance a temporary change occurred in EEG which appeared during the 1st or 2d postoperative day and which consisted of flattening and slowing of the waves of medium frequency. It was transient, independent of specific area injured, but more pronounced following larger lesions. After lesions restricted to the gray matter of the cortex there was no significant change except the transient one described above. Lesions of head of caudate or of putamen, or of both, were followed by marked changes in cortical potentials. Hypersynchrony of the 8-12 per sec. waves became intensified and the 15-20 per sec. waves became less marked or disappeared. Combined lesions of motor area with basal ganglia caused most marked changes. True epilepsy, both clinical and in EEG, was seen in 5 of 15 of these animals. All lesions causing changes in EEG produced the most marked ones in those animals operated upon in infancy.