The temporal coding of pitch: Insights from human electrophysiology

Abstract

Brian Moore and Roy Patterson have made seminal contributions to our understanding of pitch perception, and in particular the use of temporal pitch information by the auditory brain. The pitch of sounds may be encoded, at least in part, by the tendency of neurons to phase lock to the temporal fine structure and/or envelope of basilar membrane vibration. Direct physiological measures of this mechanism are difficult in humans. However, the gross activity of neurons in the brainstem can be measured using electrophysiological techniques. The frequency-following response (FFR) is an electrophysiological measure of phase locking in the rostral brainstem. The FFR differs between musicians and non-musicians, and across linguistic groups, and is sensitive to short-term pitch discrimination training. These findings suggest that the FFR may reflect neural activity relevant to the encoding of pitch, although other results suggest that it may reflect basic peripheral encoding, rather than the output of a pitch extraction process. Recent results from our laboratory show that combining behavioral and FFR measures can provide insights into the coding of the pitch of pure tones and the coding of musical consonance. The FFR may be a blunt tool, but it provides information that cannot be obtained using other techniques, and this may be particularly useful in investigations of the effects of age and hearing loss on the neural coding of pitch.