The Effects of Brain Lateralization on Motor Control and Adaptation

ABSTRACT

Lateralization of mechanisms mediating functions such as language and perception is widely accepted as a fundamental feature of neural organization. Recent research has revealed that a similar organization exists for the control of motor actions, in that each brain hemisphere contributes unique control mechanisms to the movements of each arm. The authors review present research that addresses the nature of the control mechanisms that are lateralized to each hemisphere and how they impact motor adaptation and learning. In general, the studies suggest an enhanced role for the left hemisphere during adaptation, and the learning of new sequences and skills. The authors suggest that this specialization emerges from a left hemisphere specialization for predictive control—the ability to effectively plan and coordinate motor actions, possibly by optimizing certain cost functions. In contrast, right hemisphere circuits appear to be important for updating ongoing actions and stopping at a goal position, through modulation of sensorimotor stabilization mechanisms such as reflexes. The authors also propose that each brain hemisphere contributes its mechanism to the control of both arms. They also discuss the potential advantages of such a lateralized control system.

Keywords:

• motor lateralization
• hemispheric specialization
• motor learning
• motor adaptation
• brain lateralization

ACKNOWLEDGMENTS

The authors would like to thank our colleague and friend, John Krakauer, for the many scholarly conversations about this work, and for his ideas related to our proposal of a strong and weak form of hemispheric lateralization. This study was supported by grants to Robert L. Sainburg from the National Institutes of Health, National Institute for Child Health and Human Development (R01HD39311 and R01HD059783), and grants to Kathleen Y. Haaland from the Biomedical Laboratory Research and Development Service (101BX007080) and the Rehabilitation Research and Development Service (B4125R) of the VA Office of Research and Development.