Schematic of acoustic startle reflex (ASR) under conditions of pre-pulse (pASR) or gap (gASR) inhibition.

<p>(<b>A</b>) During the pASR test animals are presented with a randomly introduced 120 dB stimulus resulting in a measurable startle response. If a 50 ms tone preceding a 50 ms silent period is introduced and detected just prior to the startle stimulus, usually a decreased startle reflex is observed. (<b>B</b>) When a startle stimulus is presented in the presence of a continuous background tone (4,8,12, 16, 20, or 24 kHz) a startle reflex is elicited. If a 50 ms silent gap in the background tone is presented just prior to the startle stimulus then the startle response is decreased. However, if an animal has tinnitus percepts and the tone matches the tinnitus in frequency and loudness then the silent gap is filled in by the animal's tinnitus and the startle response is not significantly blunted.