1 A PERCEPTUAL-MNEMONIC ROLE FOR THE PERIRHINAL CORTEX IN AGE-ASSOCIATED COGNITIVE DECLINE by Sara Nicole Burke _____________________ A Dissertation Submitted to the Faculty of the GRADUATE INTERDISCIPLINARY PROGRAM IN NEUROSCIENCE In Partial Fulfillment of the Requirements For the Degree of DOCTOR OF PHILOSOPHY In the Graduate College THE UNIVERSITY OF ARIZONA 2 0 0 9