The prevailing theory is that episodic memory -- like spatial navigation -- is positively associated with theta oscillations. Though most models of memory function suggest the most prominent theta effects should be detectable in the hippocampus, hippocampal projections may drive theta activity in neocortical areas [9], which may be more easily picked up with non-invasive recordings (see also Box 3). From this perspective, theory gives us an eminently testable hypothesis: the MTL, and regions with which it communicates, should exhibit positive correlations between the theta rhythm and the formation and retrieval of memories.
