Magnetic Stimulation of Extrastriate Body Area Impairs Visual Processing of Nonfacial Body Parts

Abstract

Functional magnetic resonance imaging indicates that observation of the human body induces a selective activation of a lateral occipitotemporal cortical area called extrastriate body area (EBA). This area is responsive to static and moving images of the human body and parts of it, but it is insensitive to faces and stimulus categories unrelated to the human body. With event-related repetitive transcranial magnetic stimulation, we tested the possible causal relation between neural activity in EBA and visual processing of body-related, nonfacial stimuli. Facial and noncorporeal stimuli were used as a control. Interference with neural activity in EBA induced a clear impairment, consisting of a significant increase in discriminative reaction time, in the visual processing of body parts. The effect was selective for stimulus type, because it affected responses to nonfacial body stimuli but not to noncorporeal and facial stimuli, and for locus of stimulation, because the effect from the interfering stimulation of EBA was absent during a corresponding stimulation of primary visual cortex. The results provide strong evidence that neural activity in EBA is not only correlated with but also causally involved in the visual processing of the human body and its parts, except the face.

Gender differences in the neural underpinning of perceiving and appreciating the beauty of the body

“…showing that EBA-rTMS impairs visual body discrimination (Urgesi et al, 2004;Urgesi, Candidi et al, 2007;Urgesi, Calvo-Merino et al, 2007;Pitcher et al, 2009). However, EBArTMS seems to affect selectively the local processing of body parts details, as shown, for example, by the finding that it interferes with matching inverted bodies, which can be discriminated only using local processing, but not with matching upright whole body figures, which can be discriminated using also configural processing (Urgesi, Candidi et al, 2007).…”

“…Indeed, while uncovering the body of opposite-gender models strongly increased the affective and attractiveness ratings of men, a much less increment was obtained in women during observation of nude vs. clothed male bodies (Costa et al, 2003). Since EBA is specifically involved in processing the form of non-facial body parts (Peelen & Downing, 2007;Urgesi et al, 2004), its alteration following rTMS may reduce the impact of body form cues on the esthetic appreciation given by men to female bodies and, therefore, reduce their final esthetic appreciation. In contrast, the same alteration in women might reduce the impact of body form processing in judging the esthetic appearance of male bodies, thus leading to an overall increase of esthetic judgments based on other cues (e.g., body implied motion).…”

“…A train of five 10 Hz rTMS pulses was delivered, starting at 150 ms after the onset of the image. The rTMS pulses were timed to interfere with the cortical processing of the image (see Urgesi, Berlucchi, & Aglioti, 2004;Urgesi, Candidi et al, 2007;Urgesi, Calvo-Merino et al, 2007). The same pulse delay and stimulation intensity was used for the three stimulation sites.…”

“…In particular, extrastriate body area (EBA) located at the posterior inferior temporal sulcus/middle temporal gyrus (Downing et al, 2001) and the fusiform body area located at the ventro-medial temporal cortex (Peelen & Downing, 2007) display a highly selective activity for visual presentations of human bodies. These areas respond selectively to photorealistic depictions of whole human bodies or body parts, still images of human bodies or body parts extending to 'stick figures' and silhouettes, in preference to human faces, images of object parts and scenes (Downing et al, 2004;2006;Peelen & Downing, 2007;Urgesi, Berlucchi & Aglioti, 2004). Interestingly, recent findings have shown that visual body representations are crucially involved during esthetical appreciation of body stimuli (Freedberg & Gallese, 2007).…”

Representation of body identity and body actions in extrastriate body area and ventral premotor cortex

“…Furthermore, self-produced movements of the limbs activate EBA 6 , suggesting a functional link between body visual representations and the action observation-execution matching systems 7 . Repetitive transcranial magnetic stimulation (rTMS) of EBA interferes with the processing of static images of human bodies 8 . However, the specific functional contributions of EBA and of the motor mirror system in the processing of bodily actions are still debated 1,9,10 .…”