Grant: Project Grant

Whether running to catch a ball or turning to reach for a coffee cup, our ability to interact with the environment depends on knowing our motion and orientation in space. As we move, the brain combines multiple sensory signals to compute estimates of our motion that we use to maintain balance, navigate, plan actions and maintain clear visual perception. This poses a challenge because different types of motion estimates are required for different tasks. For example, to keep our eyes on target as we move requires estimates of our head motion along axes centered in the head. However, when running to catch a ball, tasks such as estimating our heading direction, maintaining balance as we run, and reaching accurately to catch the ball require estimates of the axes along which the body is moving, their orientation with respect to gravity, and how the hand is displaced relative to the ball. Because no one sensor provides such estimates they must be computed by transforming and combining information from multiple sensory sources. The aim of this work is to investigate how brain circuits transform and combine multisensory signals (vestibular, proprioceptive) to compute the types of motion estimates that are essential for tasks such as postural control, locomotion and voluntary reaching. Despite the importance of these estimates for most tasks we perform every day, our understanding of how and where they are computed and the nature of the motion representations encoded remains rudimentary. Spatial disorientation, imbalance and movement disorders are particularly common in the elderly for whom the result is often loss of balance and falls resulting in significant injury. By providing a better understanding of how the brain computes and uses self-motion estimates for tasks such as postural control, navigation and goal-directed action it is hoped that this research will lead to improved diagnostic tools and rehabilitative strategies to counteract these debilitating problems.