RENEWAL OF AN EXTINGUISHED INSTRUMENTAL RESPONSE: NEURAL CORRELATES AND THE ROLE OF D1 DOPAMINE RECEPTORS A. S. HAMLIN, K. E. BLATCHFORD AND G. P. MCNALLY* School of Psychology, The University of New South Wales, Sydney, New South Wales, 2052, Australia Abstract—Contexts play an important role in controlling the expression of extinguished behaviors. We used an ABA re- newal design to study the neural correlates, and role of D1 dopamine receptors, in contextual control over extinguished instrumental responding. Rats were trained to respond for a sucrose reward in one context (A). Responding was then extin- guished in the same (A) or different (B) context. Rats were tested for responding in the original training context (A). Return to the original training context after extinction (group ABA) was associated with a return of responding. Three distinct patterns of Fos induction were detected on test: 1) ABA renewal was associated with selective increases in c-Fos protein induction in basolateral amygdala, ventral accumbens shell, and lateral hypothalamus (but not in orexin- or melanin-concentrating hormone (MCH)– hypothalamic neurons); 2) being placed in the same context as extinction training (AAA or ABB) was associated with a selective decrease in c-Fos induction in rostral agranular insular cortex; 3) being placed in any con- text on test was associated with the up-regulation of c-Fos induction in anterior cingulate, dorsomedial accumbens shell, accumbens core, lateral septum, and substantia nigra. The return of responding in ABA renewal was prevented by pre-treatment with the D1 dopamine receptor antagonist SCH23390 (10 g/kg; s.c.). SCH23390 also suppressed basal and renewal-associated c-Fos protein induction throughout accumbens, and, selectively suppressed renewal-associated c-Fos induction in lateral hypothalamus. These results sug- gest that renewal of extinguished responding for a sucrose reward depends on a distributed neural circuit involving ba- solateral amygdala, ventral accumbens shell, and lateral hy- pothalamus. D1 dopamine receptors within this circuit are essential for renewal. The results also suggest that rostral agranular insular cortex may play an important role in sup- pressing reward-seeking after extinction training. © 2006 IBRO. Published by Elsevier Ltd. All rights reserved. Key words: renewal, c-Fos, extinction, nucleus accumbens, lateral hypothalamus, rostral agranular insular cortex. Contexts play an important role in regulating the perfor- mance of learned associations. This is exemplified by their role in regulating expression of extinguished responses. Extinction is context specific (Bouton, 2002; Bouton and Swartzendruber, 1991). For example, rats trained in Pav- lovian conditioning preparations with conditioned stimulus (CS) – unconditioned stimulus (US) pairings in one context (A), then subjected to extinction training in a different con- text (B), show a loss of conditioned responding to the CS when tested in the extinction context (B), but a recovery or “renewal” of such responding when tested with the CS in the original training context (A) (ABA renewal; e.g. Bouton and Bolles, 1979; Bouton and King, 1983; Harris et al., 2000) or a novel context (C) (ABC renewal; e.g. Bouton and Bolles, 1979; Harris et al., 2000). The presence of renewal indicates that extinction training does not erase the original learning. It suggests instead that a context- dependent mask is placed on this learning. Moreover, renewal acts to reduce behavior change beyond the ther- apeutic context and therefore contributes to relapse. The behavioral and neural mechanisms for contextual control over extinguished responding have been studied exten- sively for Pavlovian conditioning, when an animal learns about the relation between a CS and a US (e.g. Bouton, 2004; Corcoran and Maren, 2001, 2004; Frohardt et al., 2000). By contrast, considerably less attention has been directed toward these mechanisms for instrumental condi- tioning, when an animal learns about the relations between its actions and their outcomes. Extinguished instrumental responding is also subject to contextual control. There is evidence for renewal of extin- guished instrumental responding for natural (e.g. Welker and McAuley, 1978; Nakajima et al., 2000, 2002) and drug rewards (e.g. Crombag and Shaham, 2002). Renewal has typically been observed when training and extinction occur in different contexts and test occurs in the training context (ABA renewal). The brain mechanisms for such renewal remain unclear. Studies of ABA renewal of instrumental responding based on drug reinforcers implicate D1 dopa- mine receptors (Crombag et al., 2002) as well as glutama- tergic neurotransmission within the ventral tegmental area and nucleus accumbens (Bossert et al., 2004, 2005). Functional inactivation studies, using microinjections of the sodium channel blocker tetrodotoxin, further implicate a distributed neural network that includes the dorsomedial prefrontal cortex, basolateral amygdala, and dorsal hip- pocampus in ABA renewal of instrumental responding for a drug reward (Fuchs et al., 2005). Thus, knowledge about the brain mechanisms for renewal of extinguished instru- mental responding is limited and based almost entirely on drug reinforcers. *Corresponding author. Tel: +61-2-93853044; fax: +61-2-93853641. E-mail address: g.mcnally@unsw.edu.au (G. P. McNally). Abbreviations: CS, conditioned stimulus; IR, immunoreactive/immuno- reactivity; MCH, melanin-concentrating hormone; MOR, -opioid receptor; NHS, normal horse serum; PB, phosphate buffer; PBS, phosphate buffer saline; PBT-X, phosphate buffer with Triton X-100; RAIC, rostral agranular insular cortex; S.E.M., standard error of the mean; TH, tyrosine hydroxylase; US, unconditioned stimulus. Neuroscience 143 (2006) 25–38 0306-4522/06$30.00+0.00 © 2006 IBRO. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.neuroscience.2006.07.035 25