Response properties of neurons in inferior colliculi of mice made susceptible to audiogenic seizures by acoustic priming.

Mice not normally susceptible to audiogenic seizures can be rendered so by exposing them to a brief intense sound during a certain developmental period (acoustic priming). To determine the effects of priming on central auditory activity, single-unit extracellular recordings were obtained from the inferior colliculi of primed C57BL/6J mice. Response patterns were observed in primed mice that were not found in nonprimed mice of the same strain. These responses were characterized by prolonged discharges to clicks and/or afterdischarges to tones in 19 of 265 units studied. For the overall sample of units, absolute thresholds were consistently elevated, low-frequency responsiveness was diminished, and the proportion of units displaying response patterns that involve inhibitory influence was reduced (onset, off, inhibition, pauser, long-latency). The incidence and rates of spontaneous activity in primed mice did not differ significantly from those found in nonprimed mice. The data suggest that acoustic priming may increase behavioral responsiveness to intense sounds by disrupting the interplay of excitation and inhibition in the central auditory system.