Human electrophysiological reflections of the recruitment of perceptual processing during actions that engage memory

The N170 event-related potential (ERP) component reflects visual perceptual processes and is known to have a source in the lateral occipital cortex (LOC) and temporal lobe regions. Convergent evidence from neuropsychological and neuroimaging studies suggests that the LOC is recruited for action tasks in which visibility of a target is unavailable and a perceptual memory of the target's characteristics must be used instead. We tested the hypothesis that the N170 reflects the contribution of additional ventral stream processes required for performing actions in which vision of a target is occluded. We predicted that the amplitude of the ERP in the latency range of the N170 would be larger when perceptual mechanisms are engaged to a greater extent. Participants were auditorily cued to touch target dots appearing on a touchscreen. Two viewing conditions varied with respect to the contribution of the ventral visuomotor stream during response initiation. In condition 1, the target disappeared with movement initiation whereas in condition 2, it disappeared with the cue to respond. The N170 during the response-initiation phase of trials was larger in amplitude for condition 2. The effect was observed over temporal electrode sites bilaterally, likely reflecting an overlap between auditory cue-related processes and additional perceptual processes within regions in the inferior-temporal cortex. Thus, the N170 may be a marker of neural activity within the ventral stream, further supporting the notion that actions initiated in the absence of a visual target rely more on perceptual representations than those directed towards visually available targets.