AES 2011 Abstract

Rationale Theta oscillations (4-8 Hz) in the hippocampus and the neocortex have been suggested to play a role in the encoding of new memories and long-term plasticity. Intracranial electrode field potential recordings provide high temporal and spatial resolution for studying these oscillations in humans during cognitive tasks. In humans, theta oscillations have been observed in many structures, including the hippocampus, during memory encoding and recall [1] and virtual maze navigation [2]. The amplitude of these oscillations was correlated to successful memory retrieval in a verbal memory task [3]. Here we characterize the encoding of memory signals at multiple temporal scales and different locations in patients with epilepsy during two complex memory tasks involving retaining sequential episodic information. We show selective modulation of theta activity for successfully recalled memories. This effort lays the groundwork for diagnostic memory testing in epilepsy patients based on quantifying a physiologic brain rhythm.