The involvement of the orbitofrontal cortex in learning under changing task contingencies

Abstract

Previous investigations examining the rat prefrontal cortex subregions in attentional-set shifting have commonly employed two-choice discriminations. To better understand how varying levels of difficulty influence the contribution of the prefrontal cortex to learning, the present studies examined the effects of orbitofrontal cortex inactivation in a two-or four-choice odor reversal learning test. Long-Evans rats were trained to dig in cups that contained distinct odors. In the twochoice odor discrimination, one odor cup was always associated with a cereal reinforcement in acquisition while the opposite odor cup was associated with a cereal reinforcement in reversal learning. In the four-choice odor discrimination, an additional two cups containing distinct odors were used that were never associated with reinforcement in acquisition or reversal learning. Bilateral infusions of the GABA-A agonist, muscimol (0.5 μg) into the orbitofrontal cortex did not impair acquisition of either the two-or four-choice discrimination task. However, muscimol infusions into the orbitofrontal cortex impaired two-and four-choice reversal learning. In the twochoice odor reversal, muscimol treatment selectively increased perseverative errors. In the fourchoice odor reversal, muscimol treatment increased perseverative, regressive, as well as irrelevant errors. These findings suggest that the orbital prefrontal cortex not only enables task switching by supporting the initial inhibition of a previously relevant choice pattern, but under increasing task demands also enables the reliable execution of a new choice pattern and reduction of interference to irrelevant stimuli.

A comparison of discrimination and reversal learning for olfactory and visual stimuli in aged rats.

“…Perseverative and regressive error patterns on the reversal task were analyzed using a criterion described in previous studies (Dias & Aggleton, 2000;Hunt & Aggleton, 1998;Kim & Ragozzino, 2005;Palencia & Ragozzino, 2004;Ragozzino et al, 1999;Ragozzino, Jih, & Tzavos, 2002a;Ragozzino, Ragozzino, Mizumori, & Kesner, 2002b;Ragozzino et al, 2003). These analyses were conducted in order to provide a more fine-grained analysis of error patterns in aged rats.…”

“…Using a criterion described in previous studies (Dias & Aggleton, 2000;Hunt & Aggleton, 1998;Kim & Ragozzino, 2005;Palencia & Ragozzino, 2004;Ragozzino et al, 1999Ragozzino et al, , 2002aRagozzino et al, , 2002bRagozzino et al, , 2003 perseverative and regressive errors committed on the olfactory and visual object reversal tasks were examined in order to obtain a more fine-grained analysis of error patterns. The results show that 24 mo old rats committed significantly more regressive errors on both the olfactory and visual object reversal tasks than did 6 mo old rats.…”

“…Lesions or temporary inactivations of the rodent prelimbic area do not impair reversal learning of a two-choice discrimination (Birrell & Brown, 2000;Boulougouris, Dalley, & Robbins, 2007;Ragozzino, Detrick, & Kesner, 1999;Ragozzino, Kim, Hassert, Minniti, & Kiang, 2003). However, lesions or pharmacological manipulations of the orbitofrontal region impair reversal learning for olfactory, tactile, or visual cues (Bohn, Giertler, & Hauber, 2003;Boulougouris et al, 2007;Chudasama & Robbins, 2003;Ferry, Lu, & Price, 2000;Izquierdo, Suda, & Murray, 2004;Kim & Ragozzino, 2005;McAlonan & Brown, 2003;Meunier, Bachevalier, & Mishkin, 1997;Rolls, Hornak, Wade, & McGrath, 1994;Schoenbaum et al, 2002aSchoenbaum et al, , 2002b. The orbitofrontal cortex may support reversal learning by governing goal-directed behavior or behavior guided by incentive values associated with a stimulus (Saddoris, Gallagher, & Schoenbaum, 2005;Schoenbaum & Roesch, 2005;Schoenbaum & Setlow, 2001;Schoenbaum, Setlow, Nugent, Saddoris, & Gallagher, 2003a;Schoenbaum, Setlow, & Ramus, 2003b;Schoenbaum, Setlow, Saddoris, & Gallagher, 2003c).…”

Differential involvement of M1-type and M4-type muscarinic cholinergic receptors in the dorsomedial striatum in task switching

“…The selective increase in regressive errors following MT-7 infusions suggests that activation of M1-type muscarinic receptors in the dorsomedial striatum does not facilitate the initial inhibition of a previously relevant choice pattern or the generation of a new choice pattern, but supports the maintenance of a new choice pattern once selected. These effects in the dorsomedial striatum contrast with lesions or temporary inactivation of the orbitofrontal cortex which also impair reversal learning, but lead to perseverative errors and not regressive errors (Chudasama & Robbins, 2003;Kim & Ragozzino, 2005). The orbitofrontal cortex is known to project to the dorsomedial striatum (Berendse, Galis-de Graaf & Groenewegen, 1992).…”

Chronic intermittent cold stress and serotonin depletion induce deficits of reversal learning in an attentional set-shifting test in rats

“…Lesions of the monkey OFC resulted in impairment of reversal learning, with normal acquisition and maintenance of attentional set (Dias et al 1996). Similarly, selective impairments in reversal learning have been observed after lesions or temporary inactivation of the rat OFC (Bohn et al 2003;Chudasama and Robbins 2003;Ferry et al 2000;Kim and Ragozzino 2005;McAlonan and Brown 2003;Schoenbaum et al 2002), again leaving new acquisition and ED set shifting capabilities intact (McAlonan and Brown 2003).…”