Alpha stimulation of the human parietal cortex attunes tactile perception to external space

Ruzzoli, Manuela; Soto-Faraco, Salvador, 1970-

doi:http://dx.doi.org/10.1016/j.cub.2013.12.029

Alpha stimulation of the human parietal cortex attunes tactile perception to external space

Citation

Ruzzoli M, Soto-Faraco S. Alpha stimulation of the human parietal cortex attunes tactile perception to external space. Curr. Biol. 2014;24(3):329-32. DOI: 10.1016/j.cub.2013.12.029

Abstract

An intriguing question in neuroscience concerns how somatosensory events on the skin are represented in the human brain. Since Head and Holmes’ [1] neuropsychological dissociation between localizing touch on the skin and localizing body parts in external space, touch is considered to operate in a variety of spatial reference frames [2]. At least two representations of space are in competition during orienting to touch: a somatotopic one, reflecting the organization of the somatosensory cortex (S1) [3], and a more abstract, external reference frame that factors postural changes in relation to body parts and/or external space [4, 5]. Previous transcranial magnetic stimulation (TMS) studies suggest that the posterior parietal cortex (PPC) plays a key role in supporting representations as well as orienting attention in an external reference frame [4, 6]. Here, we capitalized on the TMS entrainment approach [7, 8], targeting the intraparietal sulcus (IPS). We found that frequency-specific (10 Hz) tuning of the PPC induced spatially specific enhancement of tactile detection that was expressed in an external reference frame. This finding establishes a tight causal link between a concrete form of brain activity (10 Hz oscillation) and a specific type of spatial representation, revealing a fundamental property of how the parietal cortex encodes information.