The sources and intracerebral distribution of auditory evoked potentials in the alert rhesus monkey

Average auditory evoked potentials (AEP) to click stimuli were recorded from chronically implanted electrodes in alert rhesus monkeys. The cortical sources of each AEP component were identified on the basis of transcortical polarity inversions. The active loci were limited to the supratemporal plane (STP) and to a region within precentral motor cortex. Small and inconstant responses were generated in the lateral superior temporal gyrus and no locally generated activity was detected in frontal granular cortex. The responses from STP were complex, with early components generated mainly within auditory koniocortex and later components in surrounding regions. Each of these components was volume-conducted widely, both above and below the STP, and they projected onto various regions of dorsolateral surface cort(x. The volume-conducted potentials from the STP summed with the potentials generated in motor cortex to produce a complex resultant waveform. Barbiturate anesthesia abolished all but the primary AEP and reduced the volume-conducted projection of this response at the cortical surface. The configuration and intracranial distribution of the monkey AEP were compared to human intracerebral and scalp AEP recordings.