Uncovering the functional contribution of the extrastriate body area in processing body vs letter stimuli-driven...

The extrastriate body area (EBA) is a category-specific occipitotemporal cortical region highly specialized in processing visual features of corporeal stimuli and plays an essential role in body and action representation. Recent evidence suggests that body and body-part stimuli can modulate response strategies in a content-driven manner during tasks involving conflict and error monitoring. However, whether and to what extent the EBA contributes to behavioural performance during the processing of representational conflicts elicited by body stimuli remains unclear. Here, we perturbed the right EBA activity by delivering an online 10-Hz rTMS protocol while healthy participants performed two variants of the Flanker task using either letters (i.e., 'Hs' and 'Ss') or body silhouettes (i.e., narrower and wider bodies) as stimuli. The medial frontal cortex and the vertex served as active control and sham stimulation sites, respectively. Results indicate that rTMS over the rEBA modulated stimulus processing and impaired response accuracy for congruent body-related stimuli compared to sham likely inducing a target/flanker perceptual mismatch that maximized error occurrence. Furthermore, the effects of rEBA stimulation on accuracy varied by body-silhouette type, with poorer performance for narrower silhouettes regardless of flanker congruency. However, the rEBA impairment observed for congruent bodies did not emerge for incongruent bodies, possibly reflecting top-down mechanisms compensating for TMS-induced perceptual interference. In line with previous stimulation studies, these findings may support the involvement of the rEBA in the visual perception of body stimuli, even under conditions of minimal conflict and stimulus-response competition.