Parkinsonian-Related Changes in Activity of Cortical Projection Neurons
In Parkinson's disease, the brain cells that produce a chemical called dopamine are lost. This causes unusual activity in various parts of the brain responsible for movement, including the basal ganglia and motor cortex. These changes affect how the brain processes information related to movement and may contribute to the symptoms of Parkinson's disease. However, we don't fully understand how these changes in brain activity occur. In particular, changes in the primary motor cortex and the supplementary motor area of the cerebral cortex are poorly understood. Our studies are done in non-human primates which increases their significance, given the similarity in brain connections and functions between non-human primates and humans.
In this project, we study electrical activity changes in motor cortex and supplementary motor area, especially in neurons that send projections to the spinal cord. We use a retrograde viral transfection method to express light-sensitive protein (opsins) specifically in such projection cells. During our cortical experiments, these neurons can then be identified by their responses to light. We contrast the activity of neurons recorded in this way under normal and parkinsonian conditions in non-human primates.
We also investigate whether treatments that help patients with Parkinson's disease (such as levodopa treatment, or deep brain stimulation of the subthalamic nucleus) can change the abnormal cortical activities found in the parkinsonian state. It is possible that these treatments reverse some, but not all, of the identified activity changes. This information is valuable because it can guide us to develop or optimize treatments for Parkinson's disease.