Effect of thalamic lesions on spontaneous electrical activity in MES auditory cortex

¹ Department of Anatomy, University of Oregon Medical School, Portland, Oregon

Standard deviations (sd) and spatial correlation coefficients (r) of spontaneous electrical activity were computed for multiple locations on the surface of the middle ectosylvian auditory area of the dog, before and after lesions in the white matter under the area, thalamus, midbrain, and medial geniculate body. Locally applied cocaine decreased sd and increased r between locations greater than 6 mm apart from 0.3–0.5 to values > 0.75. Immediate subcortical aspiration after cocaine had no effect on sd or r, but after recovery from the cocaine, sd returned to normal and r was depressed (< 0.3–0.5) between distant locations. Lesions of the medial geniculate body decreased sd but had little effect on r. Large lesions of the thalamus produced significant decreases in r but only a moderate number of changes in sd. Lesions of the latera lemniscus caused moderate changes in sd and r.