Galvanic Vestibular Stimulation Induces a Spatial Bias in Whole-body Position Estimates

Abstract

Peripheral galvanic vestibular stimulation (GVS) has been shown to temporarily ameliorate left spatial neglect [ 1 ]. Specifically, anodal (facilitatory) stimulation over the left mastoid bone coupled with cathodal (inhibitory) over the right mastoid reduces visuospatial-neglect scores in line cancellation [ 2 ] and line bisection tasks [ 3 , 4 ]. This montage increases activity in the left vestibular nerve and suppresses activity in the right [ 5 ], which has been shown to focally activate vestibular networks that occupy visuospatial attention mechanisms, primarily in the non-dominant hemisphere [ 5 ]. Thus, it appears that electrical stimulation of the peripheral vestibular system can shift visuospatial attention to the left side of space [ 4 ]. However, whether such a shift of spatial attention in normal subjects can influence perception of spatial position during whole-body spatial translations is unknown. We hypothesized that shifting attention to the left would result in participants underestimating spatial position estimates during rightward whole-body translations and overestimating spatial position estimates during leftward whole-body translations.