Differential effects of insular and ventromedial prefrontal cortex lesions on risky decision-making

The ventromedial prefrontal cortex (vmPFC) and insular cortex are implicated in distributed neural circuitry that supports emotional decision-making. Previous studies of patients with vmPFC lesions have focused primarily on decision-making under uncertainty, when outcome probabilities are ambiguous...

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Bibliographic Details
Published in:Brain (London, England : 1878) England : 1878), 2008-05, Vol.131 (5), p.1311-1322
Main Authors: Clark, L., Bechara, A., Damasio, H., Aitken, M. R. F., Sahakian, B. J., Robbins, T. W.
Format: Article
Language:English
Subjects:
Adult
Aged
Behavior Patterns
Biological and medical sciences
Brain Damage, Chronic - pathology
Brain Damage, Chronic - psychology
Brain Hemisphere Functions
Brain Mapping - methods
Cerebral Cortex - pathology
Cerebral Cortex - physiopathology
Choice Behavior
Comparative Analysis
Decision Making
emotion
Female
Gambling
Humans
Injuries of the nervous system and the skull. Diseases due to physical agents
Magnetic Resonance Imaging - methods
Male
Medical sciences
Memory
Middle Aged
Neural Pathways - pathology
Neural Pathways - physiopathology
Neurological Impairments
Neurology
Neuropsychological Tests
neuropsychology
orbitofrontal cortex
Original
Patients
Prefrontal Cortex - pathology
Prefrontal Cortex - physiopathology
Probability
Risk
Scores
Task Analysis
Traumas. Diseases due to physical agents
uncertainty
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Summary:The ventromedial prefrontal cortex (vmPFC) and insular cortex are implicated in distributed neural circuitry that supports emotional decision-making. Previous studies of patients with vmPFC lesions have focused primarily on decision-making under uncertainty, when outcome probabilities are ambiguous (e.g. the Iowa Gambling Task). It remains unclear whether vmPFC is also necessary for decision-making under risk, when outcome probabilities are explicit. It is not known whether the effect of insular damage is analogous to the effect of vmPFC damage, or whether these regions contribute differentially to choice behaviour. Four groups of participants were compared on the Cambridge Gamble Task, a well-characterized measure of risky decision-making where outcome probabilities are presented explicitly, thus minimizing additional learning and working memory demands. Patients with focal, stable lesions to the vmPFC (n = 20) and the insular cortex (n = 13) were compared against healthy subjects (n = 41) and a group of lesion controls (n = 12) with damage predominantly affecting the dorsal and lateral frontal cortex. The vmPFC and insular cortex patients showed selective and distinctive disruptions of betting behaviour. VmPFC damage was associated with increased betting regardless of the odds of winning, consistent with a role of vmPFC in biasing healthy individuals towards conservative options under risk. In contrast, patients with insular cortex lesions failed to adjust their bets by the odds of winning, consistent with a role of the insular cortex in signalling the probability of aversive outcomes. The insular group attained a lower point score on the task and experienced more ‘bankruptcies’. There were no group differences in probability judgement. These data confirm the necessary role of the vmPFC and insular regions in decision-making under risk. Poor decision-making in clinical populations can arise via multiple routes, with functionally dissociable effects of vmPFC and insular cortex damage.
ISSN:0006-8950
1460-2156
DOI:10.1093/brain/awn066