Grant: Project Grant

Stroke can damage different regions of the brain. After the injury, patients often suffer the loss of functions of the hand. Time and rehabilitation can provide some recovery of function but it is usually incomplete. Better treatments are necessary, but to achieve this we need to understand the mechanisms involved in recovery. Some imaging studies report that after a stroke, the unaffected regions of the brain change their activity during recovery. This suggests that these spared areas could be involved in recovery. However, the way they can do so remains unclear. This is particularly a problem for the areas in the hemisphere opposite to the lesion, the contralesional hemisphere. Some studies suggest that this hemisphere helps the recovery while others show it hinders recovery, and this appears to be influenced by the location of the lesion. The broad goal of our project is to understand how lesion location affects changes in contralesional areas and, as a result, the role these areas undertake in recovery. To address these questions, we use monkeys because their motor areas are similar to the ones in humans. In different groups of animals, we will provoke lesions similar in sizes but destroying progressively more brain regions involved in the control of hand movements. During the recovery, we will record the activity of the neurons in the contralesional hemisphere and study how it changes. After the animal has completed its spontaneous recovery (without any treatment), we will use drugs to inactivate each contralesional area. This will reveal the new role the contralesional areas undertook for recovery of the paretic hand after different types of lesion. Finally, we will inject anatomical tracers and study the rewiring of connections of the contralesional areas. Our experiments will greatly increase our understanding of the mechanisms that allow contralesional areas to take a good or bad role in recovery and how the location of lesion affects these processes