P50 gating is not affected by selective attention

The influence of selective attention on P50 gating - the decline of the amplitude of the P50 component of the auditory evoked potential (AEP) to the second of a pair of clicks - was examined. Three conditions were presented in counterbalanced order to 29 18-47 year-old healthy volunteers: a baseline condition, in which the double click was presented and no specific task was required, an attention condition in which attention to the clicks was required, and a distraction condition in which paired clicks were presented during rehearsal time of a reversed digit span task. P50 gating, as measured with ratio and difference scores, did not differ across the three conditions. However, the amplitude of the N100 showed an increase in the attention condition compared to the two nonattention conditions, supporting the validity of our task manipulations. The data on P50 demonstrate that P50 gating is not affected by attentional manipulations.