Modulation of theta/alpha frequency profiles of slow auditory-evoked responses in the songbird zebra finch.

Overview

Spatiotemporal patterns of forebrain neural activity associated with auditory perception of biologically relevant complex acoustic stimuli can be conveniently studied in the songbird zebra finch. Here we present a time-frequency analysis of averaged slow auditory-evoked potentials (sAEPs) obtained at electrode locations overlying the main song control nucleus, high vocal center. Gabor spectrograms of these sAEPs show a prolonged response time course consisting of unimodal frequency peaks in the theta/alpha range (4-17 Hz). There is a stimulus-dependent modulation of the duration of the response and of the total number of its constituent frequency peaks, an effect that is bilateral in 75% of the birds and lateralized to the left side in the remaining 25%. Since the state of alertness of birds modulates these parameters along a similar continuum, these findings suggest that modulation of sAEP frequency profile may be dependent on attentional mechanisms. The presence and modulation of neurobiologically ubiquitous dominant frequency components also implicate the possible role of induced cerebral neuronal circuit oscillations in songbird auditory perception.