Behavioral flexibility is associated with changes in structure and function distributed across a frontal cortical network in macaques

Abstract

One of the most influential accounts of central orbitofrontal cortex– that it mediates behavioral flexibility – has been challenged by the finding that discrimination reversal in macaques –the classic test of behavioral flexibility –is unaffected when lesions are made by excitotoxin injection rather than aspiration. This suggests the critical brain circuit mediating behavioral flexibility in reversal tasks lies beyond the central orbitofrontal cortex. To determine its identity a group of nine macaques were taught discrimination reversal learning tasks and its impact on grey matter was measured. Magnetic resonance imaging scans were taken before and after learning and compared with scans from two control groups each comprising ten animals. One control group learned similar discrimination tasks but which lacked any reversal component and the other control group engaged in no learning. Grey matter changes were prominent in posterior orbitofrontal cortex/anterior insula but also were found in three other frontal cortical regions: lateral orbitofrontal cortex (12o), cingulate cortex, and lateral prefrontal cortex. In a second analysis, neural activity in posterior orbitofrontal cortex/anterior insula was measured at rest and its pattern of coupling with the other frontal cortical regions was assessed. Activity coupling increased significantly in the reversal learning group in comparison to controls. In a final set of experiments we used similar structural imaging procedures and analyses to demonstrate that aspiration lesion of central orbitofrontal cortex, of the type known to affect discrimination learning, affected structure and activity in the same frontal cortical circuit. The results identify a distributed frontal cortical circuit associated with behavioral flexibility.

Anatomically precise relationship between specific amygdala connections and selective markers of mental well-being in humans

“…The fourth latent measure of mental well-being we identified, anger and rejection, was also linked to areas 25 and pOFC, in addition to other frontal opercular regions that have recently been linked to the balancing of the most recent outcomes with the wider, more long-term experience of reward 61,62 .…”

Viewing Ambiguous Social Interactions Increases Functional Connectivity between Frontal and Temporal Nodes of the Social Brain

“…Faces were just part of the complex scenes being presented, and the monkeys were not explicitly required to track the faces for reward. Further, it has been argued by the co-authors that these regions within prefrontal cortex (including lateral orbital sulcus) are less concerned with face-processing per se, and more concerned with linking choices (as represented by any type of stimuli, including but not limited to faces) and outcomes (Chau et al, 2015;Lopez-Persem et al, 2020;Sallet et al, 2020). It is thus conceivable that while there might have been activation to face stimuli (over no actors) in frontal cortex, it did not achieve a sufficient signal-tonoise ratio to surpass our statistical threshold.…”