SENSORIMOTOR DEPRIVATION INDUCED BY IMMOBILIZATION MODIFIES THE KINEMATIC OF A REACHING-TO-GRASP.

M. Bassolino (1, 2) , M. Jacono (1) , M. Bove (3) , L. Fadiga (4, 1) , Thierry Pozzo (1, 5)

1 IIT - Italian Institute of Technology = Istituto Italiano di Tecnologia
2 DIST - Dipartimento di Informatica, Sistemistica e Telematica
3 Departement of Experimental Medicine, Section of Human Physiology
4 DSBTA, Section of Human Physiology
5 Motricité - Plasticité

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

Domaines: Neurosciences

M. Bassolino, M. Jacono, M. Bove, L. Fadiga, Thierry Pozzo. SENSORIMOTOR DEPRIVATION INDUCED BY IMMOBILIZATION MODIFIES THE KINEMATIC OF A REACHING-TO-GRASP.. Neuroscience, 2012, epub ahead of print. ⟨10.1016/j.neuroscience.2012.04.019⟩. ⟨hal-00705304⟩