title: Theta-gamma coupling increases during the learning of item-context associations.
abstract: Phase-amplitude cross-frequency coupling (CFC) between theta (4-12 Hz) and gamma (30-100 Hz) oscillations occurs frequently in the hippocampus. However, it still remains unclear whether theta-gamma coupling has any functional significance. To address this issue, we studied CFC in local field potential oscillations recorded from the CA3 region of the dorsal hippocampus of rats as they learned to associate items with their spatial context. During the course of learning, the amplitude of the low gamma subband (30-60 Hz) became more strongly modulated by theta phase in CA3, and higher levels of theta-gamma modulation were maintained throughout overtraining sessions. Furthermore, the strength of theta-gamma coupling was directly correlated with the increase in performance accuracy during learning sessions. These findings suggest a role for hippocampal theta-gamma coupling in memory recall.
authors.affiliation: Edmond and Lilly Safra International Institute of Neuroscience of Natal, Federal University of Rio Grande do Norte, RN 59066, Natal, Brazil. adrianotort@gmail.com
authors.forename: Adriano B L
authors.initials: AB
authors.lastname: Tort
authors.forename: Robert W
authors.initials: RW
authors.lastname: Komorowski
authors.forename: Joseph R
authors.initials: JR
authors.lastname: Manns
authors.forename: Nancy J
authors.initials: NJ
authors.lastname: Kopell
authors.forename: Howard
authors.initials: H
authors.lastname: Eichenbaum
mesh_terms: D000818:Animals; D001245:Association Learning / Q000502:physiology*; D006624:Hippocampus / Q000502:physiology; D008124:Locomotion / Q000502:physiology; D010812:Physical Stimulation; D051381:Rats; D013647:Task Performance and Analysis; D013826:Theta Rhythm