Memory is the sum of who we are. It is the bridge to our past and future. It takes a fleeting moment in our experience and allows it to last indefinitely. It stretches our consciousness over a lifetime and allows us to enjoy meaningful and fulfilling lives. Simply put, without memory, humanity as we know it could not exist. Yet, for something so essential and ubiquitous, we still know little about how it works. This talk will specifically focus on one type of memory, episodic memory, and how we can operationally define and study it using a computational or information processing approach. How does episodic memory change as we get older? What neurobiological mechanisms underlie age-related memory loss? Can we distinguish between normal age-related changes in cognition and changes related to Alzheimer’s disease? Finally, how we can use this circuit-based approach to studying cognition to better diagnose cognitive disorders?