Contrasting Roles for Orbitofrontal Cortex and Amygdala in Credit Assignment and Learning in Macaques.
Bottom Line: Recent studies have challenged the view that orbitofrontal cortex (OFC) and amygdala mediate flexible reward-guided behavior.A second experiment confirmed the existence of signals for adaptive stay/shift behavior in lOFC and reflecting irrelevant reward in the amygdala in a probabilistic learning task.Our data demonstrate that OFC and amygdala each make unique contributions to flexible behavior and credit assignment.
Affiliation: Department of Experimental Psychology, University of Oxford, OX1 3UD, Oxford, UK; Department of Psychology, The University of Hong Kong, Pokfulam Road, Hong Kong. Electronic address: email@example.com.Show MeSH
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Mentions: In this task, an optimal strategy is to stay with the same choice on the next trial after rewarded decisions but to shift to the alternative choice after non-rewarded decisions. In other words, monkeys should make use of the outcome feedback and follow a win-stay/lose-shift (WSLS) rule for guiding their behavior. Our first analysis, therefore, examined activity across the whole brain to identify regions that were sensitive to the occurrence of the outcome event of the task, regardless whether the outcome was a reward or not, using standard fMRI blood-oxygen-level-dependent (BOLD) imaging analysis procedures (see Experimental Procedures). Two example BOLD data volumes and mean BOLD data from two example sessions are shown in Figure S2A. We found that, bilaterally, lOFC became more active when the choice outcome was revealed (cluster-based thresholding z > 2.3, p < 0.05 cluster-corrected; Figure 2A). The lOFC signal was consistently found in all four animals (although in one subject the signal only exceeded the conservative threshold for significance in one hemisphere; Figure S2b). In addition, outcome-related activation was found in a number of other areas (Table S1).
Affiliation: Department of Experimental Psychology, University of Oxford, OX1 3UD, Oxford, UK; Department of Psychology, The University of Hong Kong, Pokfulam Road, Hong Kong. Electronic address: firstname.lastname@example.org.