Auditory Evoked Potentials Recorded from Different Skull Locations in the Rat

Abstract

Auditory evoked potentials were recorded from different skull sites in the rat. From over the cerebellum, the inferior colliculus, the thalamus and the auditory cortex, a series of discrete slow potentials of positive polarity were identified. The timing of these waveforms was compared with each other and with the high frequency components of the brainstem auditory evoked potential. Potentials recorded from over the inferior colliculus and the thalamus consisted of two possible responses, one of which predominated in an individual animal. Tentative origins for these slow potentials include the cerebellar cortex, the termination of the lateral lemniscus, the brachium of the inferior colliculus, the medial geniculate body, the auditory radiations and primary auditory cortex. It is concluded that as the afferent volley ascends the central auditory pathways, it generates initially the fast waves of the brainstem auditory potential followed by a series of slow positivities

Key Words:

• Auditory cortex
• brainstem auditory evoked potential
• cerebellum
• inferior colliculus
• thalamus