Asymmetrical transfer of adaptation between reaching and tracking: implications for feedforward and feedback...

Area of Science:

• Human sensorimotor control and adaptation
• Motor learning and visuomotor processes

Background:

• Reaching and manual tracking are fundamental motor tasks.
• Both tasks involve feedforward and feedback control, with emphasis on feedforward for reaching and feedback for tracking.
• The interrelation and update mechanisms of these processes are not fully understood.

Purpose of the Study:

• To investigate the bidirectional relationship between the update of feedforward and feedback processes.
• To examine how visuomotor adaptation transfers between reaching and tracking tasks.

Main Methods:

• Forty participants performed joystick-controlled reaching and pursuit tracking tasks.
• Visuomotor adaptation was induced using a 45° rotation.
• Adaptation transfer was assessed by performing tasks in different orders (reaching then tracking, or tracking then reaching).

Main Results:

• A strong asymmetrical transfer of adaptation was observed: nearly complete transfer from reaching to tracking.
• Modest transfer of adaptation was found from tracking to reaching.
• A control experiment confirmed that target predictability did not influence the tracking-to-reaching transfer.

Conclusions:

• Feedforward process updates in reaching directly contribute to feedback processes in tracking.
• Feedback processes engaged in tracking can be updated independently of feedforward adaptation.
• Reaching movements appear to be supported by more universal sensorimotor mechanisms than tracking movements.