Prestimulus cortical potentials predict the performance in a saccadic distractor paradigm

Objective: In distracter paradigms. subjects sometimes respond to the wrong stimulus in a reflex-like manner. It is poorly understood why these errors occur. Methods: To investigate the cortical processes possibly responsible for the se: errors, we recorded event-related potentials (ERPs) in human subjects p erforming a distracter saccade task in which subjects had to select a sacca de target based on the colour of the initial fixation point and ignore a di stracter on the opposite side. The initial fixation point disappeared 200 m s before the presentation of the visual stimuli (gap period). We compared t he ERPs between correct trials in which subjects looked to the correct stim ulus with error trials in which they looked towards the wrong stimulus. Results: Correct response trials and error response trials showed a negativ e potential at the end of the gap period with the greatest amplitude over t he fronto-central cortex. However. this potential had a lower amplitude in error response trials compared to correct response trials. Conclusion: These findings suggest that task-specific preparatory cortical processes in the frontal lobe prior to stimulus presentation have a major i nfluence on the performance in distracter paradigms. (C) 2001 Elsevier Scie nce Ireland Ltd. All rights reserved.