Cortical evoked potentials recorded from the guinea pig without averaging.
Potentials evoked by tonal pulses and recorded with a monopolar electrode on the pial surface over the auditory cortex of the guinea pig are presented. These potentials are compared with average potentials recorded in previous studies with an electrode on the dura. The potentials recorded by these two techniques have similar waveforms, peak latencies and thresholds. They appear to be generated within the same region of the cerebral cortex. As can be expected, the amplitude of the evoked potentials recorded from the pial surface is larger than that recorded from the dura. Consequently, averaging is not needed to extract the evoked potential once the dura is removed. The thresholds for the evoked cortical potential are similar to behavioral thresholds for the guinea pig at high frequencies; however, evoked potential thresholds are eleveate over behavioral thresholds at low frequencies. The removal of the dura and the direct recording of the evoked potential appears most appropriate for acute experiments. The recording of an evoked potential with dura electrodes empploying averaging procedures appears most appropriate for chronic studies.
D000161:Acoustic Stimulation; D000818:Animals; D001299:Audiometry; D001303:Auditory Cortex / Q000502:physiology*; D001309:Auditory Threshold; D004388:Dura Mater / Q000502:physiology; D004558:Electric Stimulation; D005071:Evoked Potentials; D006168:Guinea Pigs; D006320:Hearing Tests