Motor imagery practice may compensate for the slowdown of sensorimotor processes induced by short-term upper-limb...

Recently, it has been demonstrated that sensorimotor representations are quickly updated following a brief period of limb non-use. The present study examined the potential of motor imagery practice (MIP) and investigated the role of motor imagery instructions (kinesthetic vs. visual imagery) to counteract the functional impairment induced by sensorimotor restriction. The participants were divided into four groups. Three groups wore a splint on their left hand for 24 h. Prior to the splint removal, two of the three groups performed 15 min of MIP, with kinesthetic or visual modalities (KinMIP and VisMIP groups, respectively). The third group did not practice motor imagery (NoMIP group). Immediately after the splint removal, the participants were assessed using a hand laterality task known for evaluating sensorimotor processes. A fourth group served as the control (i.e., without immobilization and MIP). The main results showed slower left-hand response times for the immobilized NoMIP group compared with the controls. Importantly, faster response times for the left-hand stimuli appeared for the KinMIP groups only compared with the NoMIP group. No difference between the four groups was observed for the right-hand stimuli. Overall, these results highlighted the somatotopic effect of limb non-use on the efficiency of sensorimotor processes. Importantly, the slowdown of the sensorimotor processes induced by 24 h of sensorimotor deprivation may be counteracted by a kinesthetic MIP, whereas no beneficial effect appeared with visual imagery. We discuss the importance of imagery modalities for sensorimotor reactivation.