Unit Responses of the Cat Cochlear Nucleus to Amplitude-Modulated Stimuli

Abstract

Psychoacoustic studies have indicated that the pitch corresponding to the fundamental frequency of certain complex stimuli may be mediated through the temporal pattern of neural discharges. To evaluate this proposal, two populations of units from the cochlear nucleus were examined for their responses to modulated stimuli: (1) Those units with maximum sensitivity for sinusoidal stimuli of 800 Hz or less were presented with modulated stimuli having a low‐frequency fundamental, but with spectrum controlled to reduce the contribution of low‐frequency energy; (2) units with maximum sensitivity in higher‐frequency regions were studied using the stimulus frequency to which each was most sensitive and modulating it at low rates. The results suggests that units were not sensitive to the periodicity characteristics of a stimulus, per se, but that they also require certain spectral information. Once a unit is driven to respond , however, it is likely to reflect the periodicity of the stimulus in its discharge patterns.