We examined the effects of a brief period of limb immobilization on the cognitive level of action control. A splint placed on the participants' left hand was used as a means of immobilization. We used a hand mental rotation task to investigate the immobilization-induced effects on motor imagery performance (Experiments 1 and 2) and a number mental rotation task to investigate whether immobilization-induced effects are also found when visual imagery is involved (Experiment 2). We also examined whether the effects of immobilization vary as a function of individuals' vividness of motor imagery (Experiment 2). The immobilized participants performed the mental rotation tasks before and immediately after the splint removal. The control group did not undergo the immobilization procedure. For hand stimuli, response time analysis showed a lack of task-repetition benefit following immobilization (Experiments 1 and 2) except when the visual imagery task was performed first (Experiment 2). Following immobilization, a flattening in the response time profile for left hand stimuli was observed as a function of stimuli rotation (Experiments 1 and 2), especially for participants with less vivid motor imagery (Experiment 2). We did not find an immobilization-induced effect on number stimuli. These findings revealed that the cognitive representation of hand movements is modified by immobilization and that sensorimotor deprivation specifically affects motor simulation of the immobilized hand. We discuss the possibility that immobilization affects the sensorimotor system due to the reduced processing of proprioceptive feedback, which lead some participants to switch from a motor to a visual imagery strategy.

We investigated the embodied nature of motor imagery processes through a recent use-dependent plasticity approach, a short-term limb immobilization paradigm. A splint placed on the participants' left-hand during a brief period of 24 h was used for immobilization. The immobilized participants performed two mental rotation tasks (a hand mental rotation task and a number mental rotation task) before (pre-test) and immediately after (post-test) the splint removal. The control group did not undergo the immobilization procedure. The main results showed an immobilization-induced effect on left-hand stimuli, resulting in a lack of task-repetition benefit. By contrast, accuracy was higher and response times were shorter for right-hand stimuli. No immobilization-induced effects appeared for number stimuli. These results revealed that the cognitive representation of hand movements can be modified by a brief period of sensorimotor deprivation, supporting the hypothesis of the embodied nature of motor simulation processes.

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.

In the present experiment, we examined whether short-term upper-limb immobilisation would selectively affect the representation of the immobilised limb (using a hand laterality task) or if the effect of immobilisation would extend to another body part (using a foot laterality task). A rigid splint placed on the participants' left hand was used for immobilisation. A control group did not undergo the immobilisation procedure. We compared the participants' performances on the hand and foot laterality tasks before (T 1 ) and after (T 2 ) a 48-hour delay, corresponding to the immobilisation period. For controls, response time analysis indicated a benefit of task repetition for the recognition of both hand and foot images. For the immobilised group, a slowdown of performance appeared in T 2 for hand images, but not for foot images. The reduced benefit of task repetition following left-hand immobilisation appeared for both the immobilised and non-immobilised hand images. These findings revealed that the general cognitive representation of upper-limb movements is affected by the decrease in input/output signal processing due to the left-hand immobilisation, while the cognitive representation of lower-limb movements is not.

The present study aimed to investigate whether well-established associations between action and language can be altered by short-term upper limb immobilization. The dominant arm of right-handed participants was immobilized for 24 hours with a rigid splint fixed on the hand and an immobilization vest restraining the shoulder, arm, and forearm. The control group did not undergo such immobilization. In 2 experiments, participants had to judge whether a verb involved movements of the hands or feet. In Experiment 1, the response times for controls were shorter for hand-action verbs than for foot-action verbs, whereas there was no significant difference in the immobilized group. Experiment 2 confirmed these results with a pre/posttest procedure. Shorter response times were shown for hand-action verbs than for foot-action verbs in the pretests and posttests for the control group and in the pretest for the immobilized group (i.e., before immobilization). This difference was not observed for participants undergoing 24 hr of hand immobilization, who showed little progress in assessing hand-action verbs between pretest and posttest. Moreover, participants with the highest motor imagery capacities clearly demonstrated shorter response times in Experiment 2 for both hand-action and foot-action verbs, regardless of hand immobilization. Overall, these findings demonstrate for the first time that short-term sensorimotor deprivation can affect action verb processing. We discuss our results in light of the embodiment view, which considers that cognition is grounded in sensorimotor experiences. (PsycINFO Database Record

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Sensory loss involves irreversible behavioral and neural changes. Paradigms of short-term limb immobilization mimic deprivation of proprioceptive inputs and motor commands, which occur after the loss of limb use. While several studies have shown that short-term immobilization induced motor control impairments, the origin of such modifications is an open question. A Fitts' pointing task was conducted, and kinematic analyses were performed to assess whether the feedforward and/or feedback processes of motor control were impacted. The Fitts' pointing task specifically required dealing with spatial and temporal aspects (speed-accuracy trade-off) to be as fast and as accurate as possible. Forty trials were performed on two consecutive days by Control and Immobilized participants who wore a splint on the right arm during this 24 h period. The immobilization modified the motor control in a way that the full spatiotemporal structure of the pointing movements differed: A global slowdown appeared. The acceleration and deceleration phases were both longer, suggesting that immobilization impacted both the early impulse phase based on sensorimotor expectations and the later online correction phase based on feedback use. First, the feedforward control may have been less efficient, probably because the internal model of the immobilized limb would have been incorrectly updated relative to internal and environmental constraints. Second, immobilized participants may have taken more time to correct their movements and precisely reach the target, as the processing of proprioceptive feedback might have been altered.