Abstract # 48:

Scheduled for Thursday, August 17, 2006 03:15 PM-03:30 PM: Session 6 (Regency East #3) Oral Presentation

Motor Planning in Rhesus Macaques as Measured by Grip Selection

E. L. Nelson1 and M. A. Novak1,2
1Neuroscience and Behavior Graduate Program, Tobin Hall, University of Massachusetts, Amherst, MA 01003, USA, 2Psychology Department, University of Massachusetts, Amherst, MA
     Motor planning can be studied behaviorally by examining anticipatory behavior. Previous research has shown that human adults prefer grips that confer end-state comfort as opposed to start-state comfort for certain tasks. End-state comfort has also been demonstrated in children as young as four years of age. This study characterized motor planning in rhesus macaques (n=6) via initial grip selection on a task which involved opening a box with one of two handles. The handles differed in movement direction such that the handle moved either upwards or downwards. During acquisition, monkeys learned to associate color with handle direction in single box trials. Four monkeys failed to manipulate the handle, despite extensive exposure to the task. Consequently, two subjects were tested with both handles presented concurrently. One box was baited in view and the subject was then allowed to choose a single box to manipulate. Both subjects used overhand grips during acquisition regardless of handle direction. However, one subject modified her grip strategy during testing and used an underhand grip to turn the up-handle and an overhand grip to turn the down-handle, thus demonstrating end-state comfort. The other subject perseverated with the last strategy learned during acquisition. These results suggest that some monkeys are capable of refining grip strategy through motor learning and that this refinement can lead to end-state comfort grip selection in planning motor movements.