title: Peripheral nerve injury impairs the ability to maintain behavioural flexibility following acute stress in the rat.
abstract: Chronic neuropathic pain often leads to impaired cognition and reduced behavioural flexibility. This study used a rat model to investigate if a peripheral nerve injury, with or without an additional acute psychological stress, alters behavioural flexibility and goal directed behaviour as measured by sensitivity to devaluation. Neuropathic pain was induced by a chronic constriction injury (CCI) of the sciatic nerve. CCI, sham-injury and naïve rats were trained to press two levers for two rewards. In outcome devaluation tests, one of the rewards was devalued by pre-feeding it to satiety, immediately prior to an extinction test measuring responding on the two levers. The ability to preferentially direct responding toward the action earning the currently-valued reward was taken as evidence of goal-directed behaviour. To test the impact of acute stress, rats were subjected to 15min restraint following pre-feeding and prior to the devaluation test. Neither CCI surgery nor acute stress alone altered sensitivity to devaluation, but in combination CCI and acute stress significantly reduced sensitivity to devaluation. This Study demonstrates that relatively mild stressors that are without effect in uninjured populations can markedly impair cognition under conditions of chronic pain. It further suggests that overlapping neural substrates regulated by nerve injury and/or acute stress are having a cumulative effect on behavioural flexibility.
authors.affiliation: Discipline of Biomedical Sciences, School of Medical Sciences, The University of Sydney, NSW 2006, Australia. Electronic address: david.mor@sydney.edu.au.
authors.forename: David
authors.initials: D
authors.lastname: Mor
authors.affiliation: School of Psychology, The University of Sydney, NSW 2006, Australia.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Kendig
authors.affiliation: Discipline of Biomedical Sciences, School of Medical Sciences, The University of Sydney, NSW 2006, Australia.
authors.forename: James W M
authors.initials: JWM
authors.lastname: Kang
authors.affiliation: Discipline of Biomedical Sciences, School of Medical Sciences, The University of Sydney, NSW 2006, Australia.
authors.forename: Gizem
authors.initials: G
authors.lastname: Gemikonakli
authors.affiliation: Discipline of Anatomy & Histology, School of Medical Sciences, The University of Sydney, NSW 2006, Australia.
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Austin
authors.affiliation: Discipline of Anatomy & Histology, School of Medical Sciences, The University of Sydney, NSW 2006, Australia.
authors.forename: Eszter
authors.initials: E
authors.lastname: Kalman
authors.affiliation: School of Psychology, The University of Sydney, NSW 2006, Australia.
authors.forename: Laura H
authors.initials: LH
authors.lastname: Corbit
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000502:physiology*; D059350:Chronic Pain / Q000503:physiopathology / Q000523:psychology; D003216:Conditioning, Operant / Q000502:physiology*; D008297:Male; D009437:Neuralgia / Q000503:physiopathology* / Q000523:psychology; D059348:Peripheral Nerve Injuries / Q000503:physiopathology* / Q000523:psychology; D017207:Rats, Sprague-Dawley; D012149:Restraint, Physical; D012201:Reward; D012584:Sciatic Nerve / Q000293:injuries* / Q000503:physiopathology; D013315:Stress, Psychological / Q000503:physiopathology* / Q000523:psychology
keywords: Behvioural flexibility; Devaluation.; Neuropathic pain; Stress