As a postdoctoral fellow in the lab of Ben Barres at Stanford University his research focused on astrocytes, the major glial subtype in the brain. He discovered a close association between astrocytes, microglia (the resident immune cells of the brain), and abnormal neuron function. His most recent research showed that one form of reactive astrocyte is induced by factors released by microglia. These reactive astrocytes release a toxic factor that kills specific subtypes of neurons and are present in brains of patients with Alzheimer’s, Parkinson’s, Huntington’s disease, and Amyotrophic Lateral Sclerosis (Lou Gehrig’s disease), as well as in Multiple Sclerosis.