PREPULSE INHIBITION FACILITATES A LIBERAL RESPONSE BIAS IN AN AUDITORY-DISCRIMINATION TASK

THIS study examined 'prepulse inhibition' in the context of an auditor y two-tone discrimination task performed by 15 healthy subjects. In or der to distinguish between masking or excitatory information processes , weak acoustic pulses immediately preceded or succeeded a target or n on-target tone in the discrimination. Button-press performance was com pared with response in a no-pulse condition. Response bias (beta) beca me more liberal in the 100 ms prepulse and 200 ms postpulse conditions . Beta correlated with P3b amplitude measures of the event-related pot ential. The weak pulses increased temporarily the cortical excitabilit y, as measured by the decreased amplitude of the P3b component and thu s facilitated a more liberal response bias.