Where action impairs visual encoding:: an event-related fMRI study

Behavioral experiments revealed an impairment in a perceptual task when a motor task has to be planned in parallel. In two event-related fMRI experiments healthy participants performed a GO-NOGO motor task and a visual identification task. Thus, we were able to investigate the influence of a motor task on visual identification. The paradigm allowed to compare visually identical trials with and without a concurrently performed motor response. In Experiment 1, the visual task focused on shape identification, whereas in Experiment 2, the visual task focused on color identification. We found an action-dependent BOLD response modulation in extrastriate visual areas (V3, V3A in Experiment 1 and additionally V4 in Experiment 2). Thus, results demonstrate that the planning of an action has modulatory effects in brain areas concerned with early processes in visual encoding. (C) 2004 Elsevier B.V. All rights reserved.