title: Neuronal ensembles in amygdala, hippocampus, and prefrontal cortex track differential components of contextual fear.
abstract: Although the circuit mediating contextual fear conditioning has been extensively described, the precise contribution that specific anatomical nodes make to behavior has not been fully elucidated. To clarify the roles of the dorsal hippocampus (DH), basolateral amygdala (BLA), and medial prefrontal cortex (mPFC) in contextual fear conditioning, activity within these regions was mapped using cellular compartment analysis of temporal activity using fluorescence in situ hybridization (catFISH) for Arc mRNA. Rats were delay-fear conditioned or immediately shocked (controls) and thereafter reexposed to the shocked context to test for fear memory recall. Subsequent catFISH analyses revealed that in the DH, cells were preferentially reactivated during the context test, regardless of whether animals had been fear conditioned or immediately shocked, suggesting that the DH encodes spatial information specifically, rather then the emotional valence of an environment. In direct contrast, neuronal ensembles in the BLA were only reactivated at test if animals had been fear conditioned, suggesting that the amygdala specifically tracks the emotional properties of a context. Interestingly, Arc expression in the mPFC was consistent with both amygdala- and hippocampus-like patterns, supporting a role for the mPFC in both fear and contextual processing. Collectively, these data provide crucial insight into the region-specific behavior of neuronal ensembles during contextual fear conditioning and demonstrate a dissociable role for the hippocampus and amygdala in processing the contextual and emotional properties of a fear memory.
authors.affiliation: Departments of Psychology, Psychiatry & Biobehavioral Sciences, and Integrative Center for Learning and Memory, University of California, Los Angeles, California 90095.
authors.forename: Moriel
authors.initials: M
authors.lastname: Zelikowsky
authors.affiliation: Departments of Psychology, Psychiatry & Biobehavioral Sciences, and Integrative Center for Learning and Memory, University of California, Los Angeles, California 90095.
authors.forename: Sarah
authors.initials: S
authors.lastname: Hersman
authors.affiliation: Evelyn F. McKnight Brain Institute and.
authors.forename: Monica K
authors.initials: MK
authors.lastname: Chawla
authors.affiliation: Evelyn F. McKnight Brain Institute and Departments of Psychology, Neurology & Neuroscience, University of Arizona, Tucson, Arizona 85724.
authors.forename: Carol A
authors.initials: CA
authors.lastname: Barnes
authors.affiliation: Departments of Psychology, Psychiatry & Biobehavioral Sciences, and Integrative Center for Learning and Memory, University of California, Los Angeles, California 90095, mfanselow@gmail.com.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Fanselow
mesh_terms: D000679:Amygdala / Q000166:cytology / Q000502:physiology*; D000818:Animals; D004558:Electric Stimulation / Q000009:adverse effects; D005239:Fear / Q000502:physiology* / Q000523:psychology; D006624:Hippocampus / Q000166:cytology / Q000502:physiology*; D008297:Male; D009415:Nerve Net / Q000166:cytology / Q000473:pathology / Q000502:physiology*; D009474:Neurons / Q000473:pathology / Q000502:physiology*; D017397:Prefrontal Cortex / Q000166:cytology / Q000502:physiology*; D051381:Rats; D020318:Rats, Long-Evans
keywords: Arc; amygdala; catFISH; contextual fear; hippocampus; prefrontal cortex