Grant: Operating Grant

This project investigates how the brain makes decisions about voluntary actions. Recent studies motivate the hypothesis that the brain regions involved in the guidance of actions such as reaching are also involved in the process of deciding about which action to take. This hypothesis suggests that populations of neurons in the cerebral cortex, each representing a different reach direction, can simultaneously encode several potential reaching actions. These representations compete by mutually trying to suppress each other until a single winner emerges. The competition is biased by a variety of influences, including estimates of possible payoffs of the different actions, such that the most desirable action wins the competition and is released into execution. This project investigates how that competition takes place. It involves recording neural activity from the cerebral cortex of monkeys trained to perform a variety of reach decision tasks. One experiment studies how biasing influences such as the relative expected payoffs associated with different actions interact and influence neural representations of those actions. A second experiment studies how neural activity evolves while the monkey makes guesses about which action to perform. Ultimately, the project is expected to shed light both on questions of decision-making and on questions of movement planning and execution. This will lead to important insights into the neural organization of voluntary behavior and to a better understanding of both the cognitive and motor aspects of Parkinson's disease.