Revealing the body in the brain: An ERP method to examine sensorimotor activity during visual perception of...

Examining the processing of others' body-related information in the perceivers' brain across the neurotypical and clinical population is a key topic in the domain of cognitive neurosciences. We argue that beyond classical neuroimaging techniques and frequency analyses, methods that can be easily adapted to capture the fast processing of body-related information in the brain are needed. Here we introduce a novel method that allows this by measuring event-related potentials recorded with electroencephalography (ERPs-EEG). This method possesses known EEG advantages (low cost, high temporal resolution, established paradigms) plus an improvement of its main limitation; i.e., spatiotemporally smoothed resolution due to mixed neural sources. This occurs when participants are presented and process images of bodies/actions that recruit posterior visual cortices. Such stimulus-evoked activity may spread and mask the recording of simultaneous activity arising from sensorimotor brain areas, which also process body-related information. Therefore, it is difficult to dissociate the contributing role of different brain regions. To overcome this, we propose eliciting a combination of somatosensory, motor, and visual-evoked potentials during processing of body-related information (vs non-body-related). Next, brain activity from sensorimotor and visual systems can be dissociated by subtracting activity from trials containing only visual-evoked potentials to those trials containing either a mixture of visual and somatosensory or visual and motor-cortical potentials. This allows isolating visually driven neural activity in areas other than visual. To introduce this method, we revise recent work using this method, consider the processing of body-related stimuli in the brain, as well as outline key methodological aspects to-be-considered. This work provides a clear guideline to researchers interested or transitioning from behavioural to ERPs studies, offering the possibility to adapt well-established paradigms in the EEG realm to study others' body-related processing in the perceiver's own cortical body representation (e.g., examining classical EEG components in the social and embodiment frameworks).