title: Memory retrieval along the proximodistal axis of CA1.
abstract: The proximal and distal segments of CA1 are thought to perform distinct computations. Neurons in proximal CA1 are reciprocally connected with the medial entorhinal cortex (MEC) and exhibit precise spatial firing. In contrast, cells in distal CA1 communicate with the lateral entorhinal cortex (LEC), exhibit more diffuse spatial firing and are affected by the presence of objects in the environment. To determine if these segments make unique contributions to memory retrieval, we examined cellular activity along the proximodistal axis of CA1 using transgenic reporter mice. Neurons tagged during context learning in proximal CA1 were more likely to be reactivated during testing than those in distal CA1. This was true following context fear conditioning and after exposure to a novel environment. Reactivation was also higher in brain regions connected to proximal CA1 (MEC, distal CA3) than those connected to the distal segment (LEC, proximal CA3). To examine contributions to memory retrieval, we performed neurotoxic lesions of proximal or distal CA1 after training. Lesions of the proximal segment significantly impaired memory retrieval while damage to distal CA1 had no effect. These data suggest that context memories are retrieved by a hippocampal microcircuit that involves the proximal but not distal segment of CA1. © 2016 Wiley Periodicals, Inc.
authors.affiliation: Department of Psychology, Center for Neuroscience, UC Davis, Davis, California.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Nakazawa
authors.affiliation: Department of Psychology, Center for Neuroscience, UC Davis, Davis, California.
authors.forename: Aleksandr
authors.initials: A
authors.lastname: Pevzner
authors.affiliation: Department of Psychology, UC Davis, Davis, California.
authors.forename: Kazumasa Z
authors.initials: KZ
authors.lastname: Tanaka
authors.affiliation: Department of Psychology, Center for Neuroscience, UC Davis, Davis, California.|Department of Psychology, UC Davis, Davis, California.
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Wiltgen
mesh_terms: D000818:Animals; D056547:CA1 Region, Hippocampal / Q000166:cytology* / Q000502:physiology* / Q000503:physiopathology; D056654:CA3 Region, Hippocampal / Q000166:cytology / Q000502:physiology; D002452:Cell Count; D003213:Conditioning, Psychological / Q000502:physiology; D005239:Fear / Q000502:physiology; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006657:Histones / Q000235:genetics / Q000378:metabolism; D007150:Immunohistochemistry; D008568:Memory / Q000502:physiology*; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D018613:Microscopy, Confocal; D009474:Neurons / Q000166:cytology* / Q000502:physiology*; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D011897:Random Allocation; D013028:Space Perception / Q000502:physiology
chemical_list: D006657:Histones; D016760:Proto-Oncogene Proteins c-fos; D049452:Green Fluorescent Proteins
keywords: context fear; hippocampus; memory; nonspatial; spatial