The presence of another human in our immediate or distant environment is a crucial factor for survival and social behavior. Our actions vary depending on the other person's relative proximity, involving integration of brain functions subserved by neural oscillations, to generate the most appropriate behavior. This study highlights the alpha EEG role and its neural generators in interpersonal space sensitivity (IPSS). To investigate this, participants stood face-to-face, gazing into each other's eyes, while wearing a mask preventing them from staring at each other. An auditory order instructed them to alternately close and open their eyes. It was observed that alpha power of the occipito-parietal region increased as the distance decreased, transitioning from extrapersonal space (4 m) to peripersonal space (< 40 cm) when the eyes were closed. Conversely, alpha power decreased for the same distances when the eyes were open. These significant event-related synchronization (ERS) and desynchronization (ERD) effects were absent when participants' heads were masked. Beta oscillations were not significantly involved in IPSS. The number of spontaneous blinks was not significantly influenced by IPSS. Source modeling identified alpha ERS and ERD in cortical and subcortical generators significantly involved in IPSS with independent components localized in: the parietal cortex bilaterally (BA7), the left limbic gyrus (BA23), the anterior cingulate cortex (ACC) (right BA31, left and right BA24, right BA32), the right premotor cortex (BA6, including the supplementary motor area SMA), and the right frontal eye fields (BA8). These cortical areas were accompanied by the recruitment of the thalamus and cerebellum.
Cheron et al. (Wed,) studied this question.