Feedback-based training of grip force control in patients with brain damage.

Abstract

Feedback-based training of grip force control in patients with various brain lesions was evaluated. Patients were instructed to hold a force transducer in a precision grip and to track with their grip force a moving target, which was presented together with the feedback signal on a monitor. Training performance was evaluated during a maximum of 10 sessions. Before and after the training, performance in two transfer tasks, which differed in target characteristics from the training task, was examined. Ten patients with impaired grip force control, after brain lesions of different origin, were selected on the basis of a clinical examination of hand function. Tracking accuracy in training tasks and transfer tasks was evaluated by calculating the conventional root-mean-square error. Nine out of the 10 patients reduced their tracking error considerably during a maximum of 10 subsequent sessions (t test, p < 0.05), and most of them reached normal or near-normal performance. In addition, they improved in both transfer tasks (t test, p < 0.05). Detailed analysis showed that impaired initial performance and improvement was not uniform among patients and could be attributed to individual aspects of force control. In view of these results, a feedback-based training of grip force may be a useful enrichment of motor therapy.