NEURAL CORRELATES OF BEHAVIORAL GAP DETECTION IN THE INFERIOR COLLICULUS OF THE YOUNG CBA MOUSE

The gap detection paradigm is frequently used in psychoacoustics to ch aracterize the temporal acuity of the auditory system. Neural response s to silent gaps embedded in white-noise carriers, were obtained from mouse inferior colliculus (IC) neurons and the results compared to beh avioral estimates of gap detection. Neural correlates of gap detection were obtained from 78 single neurons located in the central nucleus o f the IC. Minimal gap thresholds (MGTs) were computed from single-unit gap functions and were found to be comparable, 1-2 ms, to the behavio ral gap threshold (2 ms). There was no difference in MGTs for units in which both carrier intensities were collected. Single unit responses were classified based on temporal discharge patterns to steady-state n oise bursts. Onset and primarylike units had the shortest mean MGTs (2 .0 ms), followed by sustained units (4.0 ms) and phasic-off units (4.2 ms). The longest MGTs were obtained for inhibitory neurons ((x) over bar = 14 ms). Finally, the time-course of behavioral and neurophysiolo gical gap functions were found to be in good agreement. The results of the present study indicate the neural code necessary for behavioral g ap detection is present in the temporal discharge patterns of the majo rity of IC neurons.