The National Institute of Neurological Disorders and Stroke (NINDS) encourages investigator-initiated research grant applications to study the mechanisms of transmission and dissemination of transmissible spongiform encephalopathies (TSEs). TSEs or “prion diseases” are neurodegenerative disorders that can lead to dementia, motor dysfunction and eventually death. Iatrogenic transmission of prion disease has been reported (transplantation of cadaveric cornea or dura mater, or injection of cadaveric human growth hormone); however the best known mechanism of natural transmission of TSEs is via the gastrointestinal tract through ingestion of contaminated food. Once in the digestive tract, prions are able to disseminate to the peripheral lymph organs and the Central Nervous System (CNS). This PA is intended to expand research on how these diseases can spread within an affected population and how infectious prions are then distributed through the body and ultimately to the CNS.