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  • Title: Dissociable roles of medial orbitofrontal cortex in human operant extinction learning.
    Author: Finger EC, Mitchell DG, Jones M, Blair RJ.
    Journal: Neuroimage; 2008 Dec; 43(4):748-55. PubMed ID: 18793731.
    Abstract:
    Operant extinction, which features modification of instrumental responses to stimuli following a change in associated reinforcement, is an important form of learning for organisms in dynamic environments. Animal studies have highlighted orbital and medial prefrontal cortex and amygdala as mediators of operant extinction. Yet little is known about the neural mediators of operant extinction learning in humans. Using a novel fMRI paradigm, we report dissociable functional responses in distinct regions of medial orbitofrontal cortex (mOFC) during successful appetitive and aversive based operant extinction. During successful operant extinction, increased activity was observed in frontopolar OFC, while decreased activity was observed in caudal mOFC and rostral anterior cingulate cortex (rACC) relative to both (i) successful control trials where the reinforcement associated with the stimulus does not change; and (ii) successful acquisition trials during initial learning of the stimulus-reinforcement associations. Functional connectivity analysis demonstrated inverse connectivity between frontopolar OFC and both rACC and the amygdala. These data support animal models suggesting the importance of mOFC-amygdala interaction during operant extinction and expand our knowledge of the neural systems in humans. These findings suggest that in humans, frontopolar OFC modulates activity in caudal mOFC, rACC and amygdala during successful operant extinction learning.
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