title: Functional role of gamma and theta oscillations in episodic memory.
abstract: The primary aim of this review is to examine evidence for a functional role of gamma and theta oscillations in human episodic memory. It is proposed here that gamma and theta oscillations allow for the transient interaction between cortical structures and the hippocampus for the encoding and retrieval of episodic memories as described by the hippocampal memory indexing theory (Teyler and DiScenna, 1986). Gamma rhythms can act in the cortex to bind perceptual features and in the hippocampus to bind the rich perceptual and contextual information from diverse brain regions into episodic representations. Theta oscillations act to temporally order these individual episodic memory representations. Through feedback projections from the hippocampus to the cortex these gamma and theta patterns could cause the reinstatement of the entire episodic memory representation in the cortex. In addition, theta oscillations could allow for top-down control from the frontal cortex to the hippocampus modulating the encoding and retrieval of episodic memories.
authors.affiliation: Department of Psychology and Neuroscience, University of Colorado at Boulder, Muenzinger D244, 345 UCB, Boulder, CO 80309, United States. nyhus@colorado.edu
authors.forename: Erika
authors.initials: E
authors.lastname: Nyhus
authors.forename: Tim
authors.initials: T
authors.lastname: Curran
mesh_terms: D000818:Animals; D001921:Brain / Q000502:physiology*; D006801:Humans; D008568:Memory / Q000502:physiology*; D008959:Models, Neurological; D010507:Periodicity; D013826:Theta Rhythm