The Effects of Vigilance and Visual Distraction on the P50 Mid-Latency Auditory Evoked Potential

Abstract

Sensory gating function has been investigated through measurement of the P50 evoked potential. However, the susceptibility of auditory P50 sensory gating to attentional modulation remains unclear. We sought to investigate the effects of vigilance (sustaining alertness across multiple recording blocks) and visual distraction (watching a muted movie versus a static fixation cross). We specifically chose a movie as the distracting stimulus because investigators sometimes show muted movies during P50 paradigms and the effects of this method were previously unknown. We recorded evoked potentials in a standard paired-click paradigm from groups watching a movie or static fixation cross; both groups completed four identical blocks of recording. Ratings of fatigue were recorded throughout the experiment. P50 and N100 amplitude showed signs of habituation, although N100’s amplitude reduction was more prominent than P50. P50 suppression did not change over the course of the recording session, despite increasing fatigue ratings. P50 suppression was significantly stronger for the participants who watched a movie during the recording. When comparing P50 gating results across studies, care should be taken to consider differing methodologies.