Neural Representation of Sound Duration in the Inferior Colliculus of the Mouse

In this study we examined the neuronal responses of single units to different sound durations in the inferior colliculus (IC) of the mouse. One hundred and one recorded units were classified into onset (58%), sustained (9%), on-sustained (22%), pauser (9%) and chopper (2%) response patterns. Thirty-four percent of the recorded units showing stronger responses to long stimulus durations were defined as long-duration-selective neurons. Twenty-five percent of the units preferred a narrow range of sound durations and were classified as band-pass neurons. Ten percent of the units responded preferentially to short stimulus durations and thus displayed short-duration selectivity. Twelve percent of the units that responded with nearly constant spike counts to stimuli of varying duration were classified as all-pass neurons. In contrast to the result of no short-duration-selective neurons found in chinchilla IC, we observed that some of the onset units in the IC of the mouse displayed a short duration preference. The best duration range of the duration-selective neurons in the present study corresponds to the duration range of mouse calls. We suggest that an inhibitory mechanism contributes to the duration selectivity observed in the present study.