The Animal Resources Core serves three functions: 1. Necropsy of old rats and mice to identify gross pathologic lesions that might interact with brain aging changes. 2. Screening of old rats for motor dysfunctions by the balance beam test. 3. Daily supervision of feeding protocols in the Vivarium that will supply rats (F344 males subject to diet restriction and pergolide treatment as manipulations of basal ganglia aging) for all projects and mice (genetically engineered for deficiencies of GSH).