Motor information contributes to visuotactile interaction in trunk-centered peripersonal space during a pedaling...

Peripersonal space (PPS), the space immediately surrounding one's body, contributes to interactions with the external environment. Previous studies have demonstrated that PPS expands during whole-body self-motion. Furthermore, motor and proprioceptive information contributes to this phenomenon. However, no study has disentangled the role of motor commands. Therefore, this study investigated the role of motor commands via a bike pedaling situation in a virtual reality environment. We compared three self-motion conditions: active condition where participants actively pedaled at a constant speed, passive condition where they were forced to pedal by the pedaling (exercise) device, and no-pedaling condition where they did not pedal at all. Participants observed large-field optic flow that simulated forward self-motion in all the conditions. For PPS measurements, we asked participants to quickly respond to the tactile stimulus on their chests when they observed an approaching visual probe. The PPS range was defined as the maximum distance at which the visual probe facilitated tactile detection (visual-facilitation effect). Results showed that the visual-facilitation effects were larger in the active pedaling condition than in the no-pedaling condition. Furthermore, the effects were attenuated as the probe distances from the body increased. These results suggest that motor command information can strongly contribute to PPS expansion.