Theta theory: Requirements for encoding events and task rules explain theta phase relationships in hippocampus and neocortex

Memory tasks require processes for encoding associations and retrieving them to guide goal-directed behavior (Hasselmo et al., 2002). Simulations of the interaction of hippocampus and neocortex demonstrate specific dynamical requirements required for encoding episodic memory and learning task rules. 1.) Encoding of new information without interference from previously encoded information requires cyclical transitions between encoding and retrieval states, 2.) Context dependent retrieval of task relevant information from episodic memory requires mechanism for timing and synchronization of inputs from entorhinal cortex and region CA3 to hippocampal region CA1 during retrieval. Theta theory provides a framework for describing how performance is enhanced by specific phase relationships of theta rhythm in different regions of the rat hippocampus and neocortex.