“sensorimotor Deprivation Induced by Immobilization Modifies

17 During reaching-to-grasp, the hand shape has to adapt according to the target object (the grasp 18 component) which the arm is approaching (the transport component). This requires a sophisticated 19 coordination between the two components, involving a continuum of feedforward and feedback 20 processes. A constant stream of sensorimotor information seems to be essential to successful 21 perform the task and a transient reduction of these would affect the movement. To test this 22 hypothesis, the right hand and wrist joint of 7 healthy subjects was immobilized with a removable 23 bandage for 10 hours. We compared the kinematic of a reaching-to-grasp performed before and 24 after immobilization as well as with a control group (i.e. not immobilized). Additionally, hand 25 posture was measured by recording the angular position of 16 joint angles of the fingers and thumb 26 at the time of the contact with the object. Further, time series of angular displacement were 27 analyzed by means of Principal components analysis (PCA) to evaluate a potential effect of 28 immobilization on fingers' coordination. Here we found that after immobilization the total duration 29 of reaching movement increased together with an anticipation of the time to peak velocity. 30 Moreover, the maximum grip aperture significantly increased and the hand posture at the end of the 31 grasp changed in the two groups of participants. Nevertheless, the patterns of co-variation between 32 the angular excursion of the digits remained similar before and after immobilization. All together, 33 the present findings demonstrate that a temporary reduction in sensory and motor information 34 modify the kinematic of a reaching-to-grasp both in the transport and grasp phases. However, the 35 two components showed a different recovery time course: while reach duration returned to the 36 baseline value at the lasts repetitions of the task, the maximum grip aperture increased trial after 37 trial.