Ripple Analysis in Ferret Primary Auditory Cortex III. Prediction of Unit Responses to Arbitrary Spectral Profiles

Abstract

We examined whether AI responses to arbitrary spectral profiles can be explained by the superposition of responses to the individual ripple components that make up the spectral pattern. For each unit, the ripple transfer function was first measured using ripple stimuli consisting of broadband complexes with sinusoidally modulated spectral envelopes (Shamma et al. 1994). Unit responses to various combinations of ripples were compared to those predicted from the superposition of responses according to the transfer function. Spectral profiled included combinations of 2-5 ripples of equal amplitudes and random phases, and vowel- like profiles composed of 10 ripples with various amplitudes and phases. The results demonstrate that predicted and measured responses are reasonably well matched, and hence support the notion that AI analyzes the acoustic spectrum in a substantially linear manner.