title: Auditory 40-Hz responses in the guinea pig.
abstract: Auditory evoked potentials in response to tone bursts repeated at a rate of 40 per second (auditory 40-Hz responses) were studied in the guinea pig. The potentials, consisting of a sequence of 40-Hz waves with a periodicity of about 25 msec, were distributed widely over the skull, and the largest potentials were recorded from the vertex (midline) and the temporal area contralateral to the stimulated ear. Administration of pentobarbital did not affect the midline response but reduced the amplitude of the contralateral response. Investigations of the effects of acute lesions demonstrated that the auditory 40-Hz responses from the contralateral temporal area were eliminated by aspiration of the contralateral cerebral cortex, whereas the responses from the midline continued to appear after bilateral aspiration of the cerebral cortex. The response from the midline was maintained after bilateral aspiration of the inferior colliculi, and the basic 40-Hz rhythm was still observed after decerebration. These data suggest different generation areas for the midline and contralateral 40-Hz responses in the guinea pig.
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods*; D000818:Animals; D001931:Brain Mapping; D005072:Evoked Potentials, Auditory / Q000187:drug effects; D006168:Guinea Pigs; D010424:Pentobarbital / Q000494:pharmacology
chemical_list: D010424:Pentobarbital