Control of Integrated Task Sequences Shapes Components of Reaching

ABSTRACT

Reaching toward an object usually consists of a sequence of elemental actions. Using a reaching task sequence, the authors investigated how task elements of that sequence affected feedforward and feedback components of the reaching phase of the movement. Nine right-handed adults performed, with their dominant and nondominant hands, 4 tasks of different complexities: a simple reaching task; a reach-to-grasp task; a reach-to-grasp and lift object task; and a reach-to-grasp, lift, and place object task. Results showed that in the reach-to-grasp and lift object task more time was allocated to the feedforward component of the reach phase, while latency between the task elements decreased. We also found between-hand differences, supporting previous findings of increased efficiency of processing planning-related information in the preferred hand. The presence of task-related modifications supports the concept of contextual effects when planning a movement.

Keywords:

• contextual effects
• feedback
• feedforward
• goal-directed reaching
• movement elements

ACKNOWLEDGMENTS

The authors would like to thank A. G. DelliPaoli (Kinesiology, MSU) for help with statistical analyses.

Funding

This study was funded by a Graduate Research Grant and by the Department of Physical Therapy and Rehabilitation Science (Baltimore, MD) to P. Viswanathan.