The anticipatory effect of goal-directed action planning with a lower limb on peri-personal space

Recent studies have demonstrated that the representation of peri-personal space (PPS) can be strongly modulated by the intention to execute a spatially-directed hand-movement. However, the question of whether analogous motor-induced PPS modulations can be observed during the planning and execution of goal-directed lower limbs movements has been scarcely investigated. Here we asked whether changes in the visuo-tactile PPS maps occur during the planning of a goal directed foot-movement. We asked participants to respond to the location of a tactile stimulus delivered to the index finger (top) or the thumb (bottom) of the right hand while ignoring a visual distractor presented at congruent or incongruent elevations, either close to the foot or close to the goal of the foot movement. This version of the cross-modal congruency task was performed under two different experimental conditions, as a baseline (static task, no movement involved) and embedded into a dual-task in which participants also had to plan and execute a goal-directed foot movement (dynamic task). In the static task, comparable cross-modal congruency effects (CCE) were present near the foot and near the movement goal. In the dynamic task, the CCE near the foot shrank considerably, whereas a sizable CCE was present near the movement goal. This anticipatory reweighting of the multisensory representation of near-space demonstrates that PPS is modulated by the intention to perform a goal-directed foot movement, with a weakened representation of the space around the currently occupied foot location when a movement is imminent.