The introduction is done by Dr. Steven Flanagan, Chairperson of the Department of Rehabilitation at NYU Langone Health.  Dr. Darryl Kaelin is the Endowed Chair of Stroke and Brain Injury Rehabilitation at the University of Louisville. In this Grand Rounds session, he speaks about Traumatic Brain Injury and its Association with Neurodegenerative Disorders. Part 1 Dr. Kaelin described the interesting relationship between the University of Louisville Frazier Rehabilitation Institute and NYU Rusk in New York. The Institute has its origins at NYU. His presentation had a focus on cellular level and pathophysiology that contribute to complications of brain injury, Alzheimer’s type dementia, Parkinson’s Disease and some similarities that exist. He began a literature review one-year ago on this topic, which has led to today’s discussion. It is important to start by talking a little about the pathophysiology TBI and cerebral insults. It can have some correlation to stroke and other insults to the brain and central nervous system. He also talked a little bit about things that we don’t think about much as physiatrists –astrocytes and microglia and what their roles are in the brain and in brain trauma. He indicated that astrocytes are the scaffolding or the structure upon which neurons and other cells hold themselves to and create the structure and shape of the brain. Microglial cells help in brain infection and brain inflammation. In a resting, healthy brain they are highly mobile and will undergo morphological changes following a brain trauma. He indicated that synapses between neurons are significantly affected both mechanically and in becoming lost in severe brain injury. He discussed the importance of sleep for patients with a brain injury.