title: Disruption of dentate gyrus blocks effect of visual input on spatial firing of CA1 neurons.
abstract: The role of dentate gyrus in hippocampal mnemonic processing is uncertain. One proposed role of dentate gyrus is binding internally generated spatial representation with sensory information on external landmarks. To test this hypothesis, we compared effects of visual input on spatial firing of CA1 neurons in Bax knock-out mice in which dentate gyrus neural circuitry is selectively disrupted. Whereas spatial selectivity of CA1 neuronal firing was significantly higher under normal illumination than complete darkness in wild-type mice, it was similarly low in both illumination conditions in Bax knock-out mice. Also, whereas the spatial location of neuronal firing was more stably maintained in the light than in the dark condition in wild-type mice, it was similarly unstable in both illumination conditions in Bax knock-out mice. These results show that visual input allows selective and stable spatial firing of CA1 neurons in normal animals, but this effect is lost if dentate gyrus neural circuitry is disrupted. Our results provide empirical support for the proposed role of dentate gyrus in aligning internally generated spatial representation to external landmarks in building a unified representation of external space.
authors.affiliation: Neuroscience Laboratory, Institute for Medical Sciences, Ajou University School of Medicine, Suwon 443-721, Korea.
authors.forename: Jong Won
authors.initials: JW
authors.lastname: Lee
authors.forename: Woon Ryoung
authors.initials: WR
authors.lastname: Kim
authors.forename: Woong
authors.initials: W
authors.lastname: Sun
authors.forename: Min Whan
authors.initials: MW
authors.lastname: Jung
mesh_terms: D000200:Action Potentials / Q000235:genetics / Q000502:physiology*; D000704:Analysis of Variance; D000818:Animals; D056547:CA1 Region, Hippocampal / Q000166:cytology*; D003463:Cues; D018891:Dentate Gyrus / Q000502:physiology*; D005260:Female; D008027:Light; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009474:Neurons / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D013037:Spatial Behavior / Q000502:physiology*; D013997:Time Factors; D014795:Visual Pathways / Q000502:physiology*; D051028:bcl-2-Associated X Protein / Q000172:deficiency
chemical_list: C494827:Bax protein, mouse; D051028:bcl-2-Associated X Protein