Neural binaural sensitivity at high sound speeds: Single cell responses in cat midbrain to fast-changing interaural time differences of broadband sounds

Relative motion between the body and the outside world is a rich source of information. Neural selectivity to motion is well-established in several sensory systems, but is controversial in hearing. This study examines neural sensitivity to changes in the instantaneous interaural time difference of sounds at the two ears. Midbrain neurons track such changes up to extremely high speeds, show only a coarse dependence of firing rate on speed, and lack directional selectivity. These results argue against the presence of selectivity to auditory motion at the level of the midbrain, but reveal an acuity which enables coding of fast-fluctuating binaural cues in realistic sound environments.