A Physiologically-Based Population Rate Code for Interaural Time Differences (ITDs) Predicts Bandwidth-Dependent Lateralization

Abstract

Interaural time difference (ITDs) are the most important cue to the location of sounds containing low-frequency energy (Wightmanand Kistler 1992). ITDs are encoded centrally in the medial (MSO) and lateral (LSO) superior olives which transmit the codeto the inferior colliulus (IC) (Batra et al. 1997; Goldberg and Brown 1969). Each ITD-sensitive neuron is characterized byits best ITD (BD), the one producing maximal discharge rate. It is a longstanding view that these neurons are conceptuallyarranged in an array with best frequency (BF) on one axis and BD on the other to form a labeled-line code. According to this model, the stimulus ITD corresponds to the BD (i.e. the label) of the most active neuron in the array(Jeffress 1948).