title: Orbitofrontal cortex inactivation impairs between- but not within-session Pavlovian extinction: an associative analysis.
abstract: The orbitofrontal cortex (OFC) is argued to be the neural locus of Pavlovian outcome expectancies. Reinforcement learning theories argue that extinction learning in Pavlovian procedures is caused by the discrepancy between the expected value of the outcome (US) that is elicited by a predictive stimulus (CS), and the lack of experienced US. If the OFC represents Pavlovian outcome expectancies that are necessary for extinction learning, then disrupting OFC function prior to extinction training should impair extinction learning. This was tested. In experiment 1, Long Evans rats received infusions of saline or muscimol targeting the lateral OFC prior to three appetitive Pavlovian extinction sessions. Muscimol infused into the OFC disrupted between-session but not within-session extinction behaviour. This finding was not due to muscimol infusions disrupting the memory consolidation process per se as there was no effect of muscimol infusion when administered immediately post session (experiment 2). These findings support a role for the OFC in representing outcome expectancies that are necessary for learning. A number of ways in which disrupting outcome expectancy information might block learning will be discussed in the context of traditional associative learning theories and the associative structures they depend on.
authors: School of Psychology, The University of New South Wales, Australia. Electronic address: m.panayi@unsw.edu.au.
authors: Marios C
authors: MC
authors: Panayi
authors: School of Psychology, The University of New South Wales, Australia.
authors: Simon
authors: S
authors: Killcross
mesh_terms: D000818:Animals; D001245:Association Learning / Q000187:drug effects / Q000502:physiology; D003214:Conditioning, Classical / Q000187:drug effects / Q000502:physiology; D005108:Extinction, Psychological / Q000187:drug effects / Q000502:physiology*; D058785:GABA-A Receptor Agonists / Q000494:pharmacology; D008297:Male; D008568:Memory / Q000187:drug effects / Q000502:physiology; D009118:Muscimol / Q000494:pharmacology; D017397:Prefrontal Cortex / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D020318:Rats, Long-Evans
chemical_list: D058785:GABA-A Receptor Agonists; D009118:Muscimol
keywords: Extinction; Orbitofrontal cortex; Pavlovian; Prediction error