title: Age-related decrease in theta and gamma coherence across dorsal ca1 pyramidale and radiatum layers.
abstract: In both humans and rodents, aging is linked to impairments in hippocampus dependent learning. Given such deficits, one would expect corresponding changes in hippocampal local field potentials, which represent the integration of multiple inputs onto a given dendritic field within the hippocampus. The current experiment examined coherence of theta and gamma in young and aged rats at sub-millimeter and millimeter distant locations both within and across layers in CA1 of the dorsal hippocampus. The degree to which different dendritic layers show coherent oscillations indicates the uniformity of the inputs and local circuitry, and may form an important element for processing information. Aged rats had lower coherence in all frequency ranges; this was most marked within a layer as the distance between electrodes increased. Notably, unlike younger rats, in the aged rats coherence was not affected by running on the maze. Furthermore, despite the previously reported effects of cholinergic activation on theta frequency and power, there was no effect of the cholinomimetic physostigmine on coherence. These data indicate an age related fragmentation in hippocampal processing that may underlie some of the observed learning and memory deficits.
authors.affiliation: Departments of Psychology, University of Connecticut, Storrs, Connecticut.
authors.forename: Tara K
authors.initials: TK
authors.lastname: Jacobson
authors.affiliation: Departments of Psychology, University of Connecticut, Storrs, Connecticut.
authors.forename: Brandy
authors.initials: B
authors.lastname: Schmidt
authors.affiliation: Departments of Psychology, University of Connecticut, Storrs, Connecticut.
authors.forename: James R
authors.initials: JR
authors.lastname: Hinman
authors.affiliation: Departments of Psychology, University of Connecticut, Storrs, Connecticut.|Departments of Biomedical Engineering, University of Connecticut, Storrs, Connecticut.|Departments of Electrical and Computer Engineering, University of Connecticut, Storrs, Connecticut.
authors.forename: Monty A
authors.initials: MA
authors.lastname: Escabí
authors.affiliation: Departments of Psychology, University of Connecticut, Storrs, Connecticut.
authors.forename: Etan J
authors.initials: EJ
authors.lastname: Markus
mesh_terms: D000367:Age Factors; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology*; D056547:CA1 Region, Hippocampal / Q000502:physiology*; D002800:Cholinesterase Inhibitors / Q000494:pharmacology; D065818:Gamma Rhythm / Q000502:physiology*; D008297:Male; D018782:Maze Learning / Q000502:physiology*; D010830:Physostigmine / Q000494:pharmacology; D051381:Rats; D011916:Rats, Inbred F344; D013826:Theta Rhythm / Q000502:physiology*
chemical_list: D002800:Cholinesterase Inhibitors; D010830:Physostigmine
keywords: EEG; cholinergic; encoding; hippocampus; local field potentials; novelty; oscillations; physostigmine