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

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.