FMRI adaptation reveals a cortical mechanism for the coding of space near the hand

Abstract

Behavioral studies in humans and electrophysiological recordings in nonhuman primates have suggested the existence of a specific representation of the space immediately surrounding the body. In macaques, neurons that have visual receptive fields limited to a region of space close around a body part have been found in premotor and parietal areas. These cells are hypothesized to encode the location of external objects in coordinate systems that are centered on individual body parts. In the present study, we used an fMRI adaptation paradigm on healthy participants to reveal areas in the anterior part of the intraparietal sulcus, the inferior parietal lobe (supramarginal gyrus), and the dorsal and ventral portions of the premotor cortex that exhibit selective BOLD adaptation to an object moving near the right hand. Crucially, these areas did not manifest adaptation if the stimulus was presented in far space (100 cm) or when the hand was retracted from the object. This hand-centered selectivity could not be detected when at raditional fMRI analysis approachwasused.These findings are importantasthey provide the most conclusive neuroimaging evidence to date for arepresentationof near-personal space in thehumanbrain. They also demonstrateaselective mechanism implemented by human perihand neuronsinthe premotorandposterior parietal areas and add to earlier findings from humans and nonhuman primates. © 2011 the authors.