The insula is a brain structure implicated in disparate cognitive, affective, and regulatory functions, including interoceptive awareness, emotional responses, and empathic processes. While classically considered a limbic region, recent evidence from network analysis suggests a critical role for the insula, particularly the anterior division, in high-level cognitive control and attentional processes. The crucial insight and view we present here is of the anterior insula as an integral hub in mediating dynamic interactions between other large-scale brain networks involved in externally oriented attention and internally oriented or self-related cognition. The model we present postulates that the insula is sensitive to salient events, and that its core function is to mark such events for additional processing and initiate appropriate control signals. The anterior insula and the anterior cingulate cortex form a “salience network” that functions to segregate the most relevant among internal and extrapersonal stimuli in order to guide behavior. Within the framework of our network model, the disparate functions ascribed to the insula can be conceptualized by a few basic mechanisms: (1) bottom–up detection of salient events, (2) switching between other large-scale networks to facilitate access to attention and working memory resources when a salient event is detected, (3) interaction of the anterior and posterior insula to modulate autonomic reactivity to salient stimuli, and (4) strong functional coupling with the anterior cingulate cortex that facilitates rapid access to the motor system. In this manner, with the insula as its integral hub, the salience network assists target brain regions in the generation of appropriate behavioral responses to salient stimuli. We suggest that this framework provides a parsimonious account of insula function in neurotypical adults, and may provide novel insights into the neural basis of disorders of affective and social cognition.

/pdf/saliency-switching-attention-and-control-a-network-model-of-4nzu8lqybn.pdf

Saliency, switching, attention and control: a network model of insula function

http://www.brainresearch.us/cognitive.pdf

The cognitive control of emotion.

Social interaction is a cornerstone of human life, yet the neural mechanisms underlying social cognition are poorly understood. Recently, research that integrates approaches from neuroscience and social psychology has begun to shed light on these processes, and converging evidence from neuroimaging studies suggests a unique role for the medial frontal cortex. We review the emerging literature that relates social cognition to the medial frontal cortex and, on the basis of anatomical and functional characteristics of this brain region, propose a theoretical model of medial frontal cortical function relevant to different aspects of social cognitive processing.

http://people.uncw.edu/tothj/PSY595/Amodio-Social%20Cognition-NRN-2006.pdf

Meeting of minds: the medial frontal cortex and social cognition.

https://www.cell.com/trends/cognitive-sciences/pdf/S1364-6613(04)00053-1.pdf

Inhibition and the right inferior frontal cortex.

Cognitively demanding tasks that evoke activation in the brain's central-executive network (CEN) have been consistently shown to evoke decreased activation (deactivation) in the default-mode network (DMN). The neural mechanisms underlying this switch between activation and deactivation of large-scale brain networks remain completely unknown. Here, we use functional magnetic resonance imaging (fMRI) to investigate the mechanisms underlying switching of brain networks in three different experiments. We first examined this switching process in an auditory event segmentation task. We observed significant activation of the CEN and deactivation of the DMN, along with activation of a third network comprising the right fronto-insular cortex (rFIC) and anterior cingulate cortex (ACC), when participants perceived salient auditory event boundaries. Using chronometric techniques and Granger causality analysis, we show that the rFIC-ACC network, and the rFIC, in particular, plays a critical and causal role in switching between the CEN and the DMN. We replicated this causal connectivity pattern in two additional experiments: (i) a visual attention "oddball" task and (ii) a task-free resting state. These results indicate that the rFIC is likely to play a major role in switching between distinct brain networks across task paradigms and stimulus modalities. Our findings have important implications for a unified view of network mechanisms underlying both exogenous and endogenous cognitive control.

https://www.pnas.org/content/pnas/105/34/12569.full.pdf

A critical role for the right fronto-insular cortex in switching between central-executive and default-mode networks

Summary How do the frontal lobes support behavioural flexibility? One key element is the ability to adjust responses when the reinforcement value of stimuli change. In monkeys, this ability—a form of affective shifting known as reversal learning—depends on orbitofrontal cortex. The present study examines the anatomical bases of reversal learning in humans. Subjects with lesions of the ventromedial prefrontal cortex were compared with a group with dorsolateral frontal lobe damage, as well as with normal controls on a simple reversal learning task. Neither form of frontal damage affected initial stimulus‐reinforcement learning; ventromedial frontal damage selectively impaired reversal learning.

/pdf/ventromedial-frontal-cortex-mediates-affective-shifting-in-44vo43g5a8.pdf

Ventromedial frontal cortex mediates affective shifting in humans: evidence from a reversal learning paradigm

Ventromedial prefrontal cortex (VMF) damage can lead to impaired decision-making. This has been studied most intensively with the Iowa gambling task (IGT), a card game that asks subjects to overcome an initial attraction to high-payoff decks as losses begin to accrue. VMF subjects choose from the high risk decks more often than controls, but the fundamental impairments driving poor performance on this complex task have yet to be established. There is also conflicting evidence regarding the role of the dorsolateral prefrontal cortex (DLF) in this task. The present study examined whether poor performance on the IGT was specific for VMF damage and whether fundamental impairments in reversal learning contributed to IGT performance. We found that both VMF and DLF damage leads to impaired IGT performance. The impairment of VMF subjects, but not of DLF subjects, seems to be largely explained by an underlying reversal learning deficit.

/pdf/different-underlying-impairments-in-decision-making-280ue3wo35.pdf

Different Underlying Impairments in Decision-making Following Ventromedial and Dorsolateral Frontal Lobe Damage in Humans

Food and drug cues activate similar brain regions: a meta-analysis of functional MRI studies.

Ventromedial prefrontal cortex (VMF) is thought to be important in human decision making, but studies to date have focused on decision making under conditions of uncertainty, including risky or ambiguous decisions. Other lines of evidence suggest that this area of the brain represents quite basic information about the relative ‘‘economic’’ value of options, predicting a role for this region in value-based decision making even in the absence of uncertainty. We tested this prediction in human subjects with VMF damage. Preference judgment is a simple form of value-based decision making under certainty. We asked whether VMF damage in humans would lead to inconsistent preference judgments in a simple pairwise choice task. Twenty-one participants with focal damage to the frontal lobes were compared with 19 age- and educationmatched control subjects. Subjects with VMF damage were significantly more inconsistent in their preferences than controls, whereas those with frontal damage that spared the VMF performed normally. These results argue that VMF plays a necessary role in certain as well as uncertain decision making in humans.

https://www.mcgill.ca/decisionlab/files/decisionlab/fellows_farah_2007_the_role_of_ventromedial_prefrontal_cortex_in_decision_making.pdf

The Role of Ventromedial Prefrontal Cortex in Decision Making: Judgment under Uncertainty or Judgment Per Se?

Summary Functional neuroimaging studies in normal humans suggest that dorsal anterior cingulate cortex (dACC) plays an important role in cognitive control. This brain area is reliably activated when tasks require the ongoing adjustment of the allocation of attention. The dACC has come to occupy a central role in theories of attention and cognitive control, which hold that dACC either monitors response conflict, signalling the need for adjustments in cognitive processes, or directly mediates such adjustments. However, functional imaging results cannot establish that a brain area is necessary for a particular cognitive process. This requires evidence from loss-offunction studies. Here we assessed cognitive control in four human subjects with damage to dACC and 12 ageand education-matched control subjects using several measures drawn from the functional imaging literature. All four subjects with dACC damage showed normal adjustments in performance following manipulation of response conflict in both Stroop and go‐no go tasks. Furthermore, damage to the dACC did not impair the phenomenon of post-error slowing, nor alter the ability to adjust performance in response to explicit speed or accuracy instructions. Thus, cognitive control, as assessed by four different measures in two different tasks, appears to be intact in these subjects, arguing against a necessary role for dACC in this process.

/pdf/is-anterior-cingulate-cortex-necessary-for-cognitive-control-3tvicuowej.pdf

Lesley K. Fellows

Papers

Ventromedial frontal cortex mediates affective shifting in humans: evidence from a reversal learning paradigm

Different Underlying Impairments in Decision-making Following Ventromedial and Dorsolateral Frontal Lobe Damage in Humans

Food and drug cues activate similar brain regions: a meta-analysis of functional MRI studies.

The Role of Ventromedial Prefrontal Cortex in Decision Making: Judgment under Uncertainty or Judgment Per Se?

Is anterior cingulate cortex necessary for cognitive control