Figure 1

Auditory stimuli for prepulse inhibition. A), a single sine wave 1 ms in duration was repeatedly presented at 100 Hz. B), the standard or background stimulus was a train of click sounds 70 dB SPL in sound pressure and 600 ms in duration. The test stimulus to evoke change-related cortical responses consisted of a similar train of clicks of 70 dB for 400 ms followed by 80 dB clicks for 200 ms. One click of 75 dB was inserted before the test stimulus as a prepulse.