Abstract
The ability to coordinate two hands/arms to accomplish a variety of tasks, from opening a bottle of wine to playing the piano, is essential for our daily lives. In contrast to the control of single arm movements, the control of bimanual movements is still poorly understood. In my talk, I will present two behavioural studies where we investigated how the movement of two arms is encoded in the controller of each arm during bimanual reaching movements.
In the first study, we show that desired movement directions for both arms are multiplicatively integrated in the controller. Modelling work and additional experiments suggest that such multiplicative encoding may be the foundation of flexible bimanual coordination, helping to create an arbitrary mapping between the desired movement kinematics of both arms and the motor output of each arm. In the second study, we demonstrated the asymmetry of this multiplicative encoding. We found that, for right-handed subjects, the controller for the left arm encodes information about the right arm movement sharply. In contrast, the controller for the right arm encodes information about the left arm movement weakly. Critically, this leads to a hypothesis that the non-dominant arm is surprisingly more flexible than the dominant arm in adapting to changes in the other arm. Further modelling and experiments supported this hypothesis. We suggest that such functional specialisation of the two arms may help efficient bimanual coordination by facilitating effective role assignment to each arm.