Grip force scaling and sequencing of events during a manipulative task in Huntington's disease

Thr aim of the study was to investigate force regulation and sequencing of events in Huntington's disease (HD) patients when performing a drawer openi ng task using the precision grip. Results revealed that HD patients used ex cessive grip force levels that were unrelated to the actual task demands. A lso. they demonstrated a higher grip force value at load force onset in add ition to an increased delay between initiation of grip force and load (pull ing) force. These data indicate a deficit in the coordinated activation of both forces due to HD. Furthermore, the patients showed bradykinesia along with a prolonged interval between the movement phases underlying the task, denoting an impairment in encoding serially ordered events. Together. these results illustrate the deteriorating effect of striatal pathology on manua l function. Accordingly, an amended control of grasping forces and serial e ncoding of movement-related events due to HD are likely to affect the profi ciency of common manipulative skills. (C) 2001 Elsevier Science Ltd. All ri ghts reserved.