title: State-dependent columnar organization of dorsal hippocampal activity in the freely-behaving cat.
abstract: We examined reflected light images from the dorsal hippocampus in freely-behaving cats to assess the topographical organization of neural activity expressed during sleep-waking states. Reflectance patterns, organized as columns along the CA3-CA1 axis which appeared during rapid eye movement sleep (REM) and waking states, were compared to baseline periods collected during quiet sleep (QS). The columns were not static across states or behaviors within a state, but showed inversion in activation/inactivation patterns, and narrowed or widened over time. A correlation between state-dependence and reflectance patterns emerged, with transitions to active waking and REM most likely exhibiting enhanced columnar patterning, relative to QS. No columnar patterns appeared in overlying neocortical areas or in control media. The columnar patterns suggest a highly structured functional state-dependent organization in the dorsal hippocampus, as has been previously predicted by anatomical studies.
authors.affiliation: Department of Anesthesiology, University of Michigan, Ann Arbor, MI 48109-0615, USA.
authors.forename: Gina R
authors.initials: GR
authors.lastname: Poe
authors.forename: David M
authors.initials: DM
authors.lastname: Rector
authors.forename: Ronald M
authors.initials: RM
authors.lastname: Harper
mesh_terms: D000818:Animals; D001931:Brain Mapping; D002415:Cats; D006624:Hippocampus / Q000033:anatomy & histology / Q000502:physiology*; D009415:Nerve Net / Q000033:anatomy & histology / Q000502:physiology; D009474:Neurons / Q000000981:diagnostic imaging / Q000502:physiology; D017286:Polysomnography; D012894:Sleep Stages / Q000502:physiology*; D012895:Sleep, REM / Q000502:physiology; D014463:Ultrasonography; D014851:Wakefulness / Q000502:physiology*