Modulation of prepulse inhibition by an augmented acoustic environment in DBA/2J mice.

DBA/2J (DBA) mice exhibit progressive hearing loss, evident for high frequencies (>20 kHz) at age 3-4 weeks and severe by 12-16 weeks. From age 25 days to 12 weeks, DBA mice were exposed for 12 hr nightly to an augmented acoustic environment (AAE): moderately intense broadband noise bursts. After AAE treatment, prepulse inhibition (PPI) to tone prepulses (4-24 kHz, 70 dB SPL) was stronger, and baseline acoustic startle responses were larger, compared with results for age-matched DBA mice (testing performed with AAE off). Nightly AAE treatment was then terminated, and both AAE effects were largely gone 1 week later. Reinstatement of AAE treatment after the 4-week period had no significant effect on startle magnitude, but PPI improved significantly, with the AAE effect reacquired after 3 weeks. It is proposed that AAE modulates neural plasticity induced by high-frequency hearing loss in auditory system components of the PPI pathway.