Middle and long latency auditory evoked potentials in cat. I. Component definition and dependence on behavioral factors

Abstract

Middle (IO-50 ms) and long (50-600 ms) latency auditory evoked potentials (AEPs) were investigated in artificially respired, muscle-paralyzed cats. Similarity to human potentials of comparable latencies was examined in two ways: (1) the similarity of waveform features such as peak amplitude, polarity and latency, and (2) the effects of task-related variables on these various waveform features. Four behavioral variations of a classical pupillary conditioning paradigm were used to vary attention and arousal. Twelve peaks and troughs were identified in the AEP: PIO, N13, P17. N22. P31, N41. P55, N70, NIOO. Nl40. P260 and N520. Principal components analysis (PCA) defined 7 AEP components, some of which spanned several peaks. Analysis both of peak latencies and amplitudes.and of principal component scores, revealed differential effects of the behavioral manipulations on these components: those with latencies longer than 50 ms were strongly influenced by behavioral variations, while earlier components were relatively immune to these effects. On the basis of these findings. several relationships between cat and human AEP components were suggested. Specifically, peaks PlO-P41 in the cat were thought related to human middle latency components, cat P55 to human P50. cat N 140 to human N300. and cat P260 to human P300. Cat N520 was comparable to several long latency components in humans, No obvious correspondences between cat AEP components and human N90 and PI70 were identified.

Middle and long latency auditory evoked potentials in cat. II. Component distributions and dependence on stimulus factors

“…We previously noted the similar waveshape of cat and human AEPs at latencies between 10 and 45 ms [6], and the fact that these cat components were little affected by behavioral task [6], similar to human AEPs [19], although some reduction in amplitude had been reported for deeper sleep in humans [ 19-211. Stimulus intensity changes strongly influenced these components' amplitudes, both in this study, and in comparable human studies [ 16-18,351.…”

“…Cat P55 resembles human P50 in latency and polarity [6]. It also shows parameter amplitude changes with stimulus intensity, and is more strongly evoked by longer duration stimuli.…”

“…The components of the cat AEP wit1 now be compared to human AEP components on the basis of both the current data and data presented previously [6,36] concerning their waveshape and behavioral correlates.…”

“…The methods used to derive the data on skull surface distributions of cat AEP components have been completely described in a companion paper (6).…”

“…Data were retrieved from tape and digitized in a manner similar to that described for the behavioral study [6], except that a sample of 200 clicks and 150 noise bursts were used to form the AEPs. Further analysis, including score calculation and statistical analyses, will be described in appropriate portions of the results sections.…”