The brainstem auditory evoked potential: effects of high frequency filtering.
The effects of low pass filtering on the brainstem auditory evoked potential (BAEP) were studied in the lightly anaesthetised rat. The high pass filter was kept fixed at 100 Hz in order to exclude the slow components on which the four fast waves of the BAEP are superimposed. The cut-off frequency of the low pass filter was systematically raised from 160 to 32 k HZ. With a band pass of 100-160 Hz, the BAEP waveform could barely be discerned. With a bandpass of 100-320 Hz, all four BAEP waves were apparent but of diminutive amplitude. With subsequent increases in the high frequency cut-off, the BAEP waveform became more clearly defined with increases in the amplitudes and decreases in the latencies of all four waves. However, beyond 8 k Hz, there was little additional change in waveform morphology. With widening of the bandpass, there was only a small concomitant decrease in brainstem transmission time. This implies that the effects of low pass filtering acted in a basically uniform manner on all four BAEP waves.
Shaw
N A
NA
Department of Physiology, School of Medicine, University of Auckland, New Zealand.
D000818:Animals; D001306:Auditory Pathways / Q000502:physiology; D001933:Brain Stem / Q000502:physiology*; D004867:Equipment Design; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D008297:Male; D009482:Neurophysiology / Q000295:instrumentation; D051381:Rats