Neurobiology of decision-making: risk and reward

Neurological patients with bilateral ventromedial (VM) lesions of the prefrontal cortex often deny, or they are not aware that they have a problem. Furthermore, they often pursue actions that bring some reward in the immediate run, despite severe long-term consequences such as the loss of job, home, and family. The somatic marker hypothesis, which provides an account of this defect in decision-making, posits that the impairment is the result of defective activation of somatic markers that normally function as covert or overt signposts for helping with the process of making choices that are advantageous to the organism. Failure to enact somatic states results from dysfunction in a neural system in which the VM cortex is one critical region. However, other neural regions, including the amygdala, and somatosensory cortices (SI, SII, and insula) are also hypothesized to be components of that same neural system. Recent evidence reveals that substance abusers suffer from decision-making deficit akin to that seen with patients with VM lesions. Thus, the strategies used to study decision-making in neurological patients have direct implications for understanding several neuropsychiatric disorders including addiction and pathological gambling.