title: Neural structures mediating expression and extinction of platform-mediated avoidance.
abstract: Individuals use both passive and active defensive responses to environmental threats. Much is known about the neural circuits of passive defensive responses (e.g., freezing), but less is known about the substrates of active defensive responses (e.g., avoidance). We developed an active avoidance task in which rats learn to avoid a tone-signaled footshock by stepping onto a nearby platform. An advantage of this task is that freezing, which can interfere with avoidance, is reduced, thereby facilitating comparison of the effects of manipulations on avoidance versus freezing. After 10 d of avoidance training, rats were infused with muscimol to pharmacologically inactivate the prelimbic cortex (PL), infralimbic cortex (IL), ventral striatum (VS), or basolateral amygdala (BLA). Inactivating PL, VS, or BLA all impaired avoidance expression, but these areas differed with respect to freezing. Inactivating BLA decreased freezing consistent with loss of the tone-shock association, whereas inactivation of VS increased freezing consistent with loss of avoidance memory. Inactivation of PL had no effect on freezing. Inactivation of IL did not impair avoidance expression but did impair avoidance extinction. Our findings suggest that active avoidance is mediated by prefrontal-striatal circuits, which may be overactive in individuals suffering from trauma-related disorders.
authors.affiliation: Departments of Psychiatry and Anatomy & Neurobiology, University of Puerto Rico School of Medicine, San Juan, Puerto Rico 00936-5067.
authors.forename: Christian
authors.initials: C
authors.lastname: Bravo-Rivera
authors.affiliation: Departments of Psychiatry and Anatomy & Neurobiology, University of Puerto Rico School of Medicine, San Juan, Puerto Rico 00936-5067.
authors.forename: Ciorana
authors.initials: C
authors.lastname: Roman-Ortiz
authors.affiliation: Departments of Psychiatry and Anatomy & Neurobiology, University of Puerto Rico School of Medicine, San Juan, Puerto Rico 00936-5067.
authors.forename: Edith
authors.initials: E
authors.lastname: Brignoni-Perez
authors.affiliation: Departments of Psychiatry and Anatomy & Neurobiology, University of Puerto Rico School of Medicine, San Juan, Puerto Rico 00936-5067.
authors.forename: Francisco
authors.initials: F
authors.lastname: Sotres-Bayon
authors.affiliation: Departments of Psychiatry and Anatomy & Neurobiology, University of Puerto Rico School of Medicine, San Juan, Puerto Rico 00936-5067 gregoryjquirk@gmail.com.
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Quirk
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001362:Avoidance Learning / Q000502:physiology*; D001921:Brain / Q000187:drug effects / Q000502:physiology*; D001931:Brain Mapping; D003216:Conditioning, Operant / Q000187:drug effects / Q000502:physiology; D005108:Extinction, Psychological / Q000502:physiology*; D005239:Fear / Q000187:drug effects / Q000502:physiology; D046352:Freezing Reaction, Cataleptic / Q000187:drug effects / Q000502:physiology; D058785:GABA-A Receptor Agonists / Q000494:pharmacology; D008297:Male; D009118:Muscimol / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D058785:GABA-A Receptor Agonists; D009118:Muscimol
keywords: amygdala; fear; infralimbic; prefrontal; prelimbic; striatum