title: Disruption of the perineuronal net in the hippocampus or medial prefrontal cortex impairs fear conditioning.
abstract: The perineuronal net (PNN) surrounds neurons in the central nervous system and is thought to regulate developmental plasticity. A few studies have shown an involvement of the PNN in hippocampal plasticity and memory storage in adult animals. In addition to the hippocampus, plasticity in the medial prefrontal cortex (mPFC) has been demonstrated to be critical for the storage of long-term memory, particularly memories for temporally separated events. In the present study, we examined the role of PNN in the acquisition and retention of memories for trace (in which the conditioned and unconditioned stimuli are temporally separated) and delayed (in which the conditioned and unconditioned stimuli overlap) fear conditioning in both the hippocampus and the mPFC. Consistent with a role for the hippocampus in memory storage in both delayed and trace fear conditioning, removal of hippocampal PNN disrupted contextual and trace fear memory. Disruption of the PNN in the mPFC impaired long-term trace and conditioned stimulus (CS)-elicited fear memory in the trace fear conditioning task. Interestingly, CS-elicited fear memory was also impaired when a delayed fear conditioning paradigm was used. These findings further support a role for the PNN in neural plasticity and implicate PNN-regulated plasticity in neocortical memory storage.
authors.affiliation: Department of Neurobiology and Anatomy, University of Texas Medical School, Houston, Texas 77225, USA.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Hylin
authors.forename: Sara A
authors.initials: SA
authors.lastname: Orsi
authors.forename: Anthony N
authors.initials: AN
authors.lastname: Moore
authors.forename: Pramod K
authors.initials: PK
authors.lastname: Dash
mesh_terms: D000818:Animals; D019765:Chondroitin ABC Lyase / Q000494:pharmacology; D003214:Conditioning, Classical / Q000187:drug effects / Q000502:physiology*; D005109:Extracellular Matrix / Q000187:drug effects / Q000502:physiology*; D005239:Fear / Q000187:drug effects / Q000502:physiology*; D006624:Hippocampus / Q000187:drug effects / Q000502:physiology*; D006821:Hyaluronoglucosaminidase / Q000494:pharmacology; D008297:Male; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D017397:Prefrontal Cortex / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D020318:Rats, Long-Evans
chemical_list: D006821:Hyaluronoglucosaminidase; D019765:Chondroitin ABC Lyase