FAILURE TO RESPOND AUTONOMICALLY TO ANTICIPATED FUTURE OUTCOMES FOLLOWING DAMAGE TO PREFRONTAL CORTEX

Following damage to specific sectors of the prefrontal cortex, humans develop a defect in real-life decision making, in spite of otherwise n ormal intellectual performance. The patients so affected may even real ize the consequences of their actions but fail to act accordingly, thu s appearing oblivious to the future. The neural basis of this defect h as resisted explanation. Here we identify a physiological correlate fo r the defect and discuss its possible significance. We measured the sk in conductance responses (SCRs) of 7 patients with prefrontal damage, and 12 normal controls, during the performance of a novel task, a card game that simulates real-life decision making in the way it factors u ncertainty, rewards, and penalties. Both patients and controls generat ed SCRs after selecting cards that were followed by penalties or by re ward. However, after a number of trials, controls also began to genera te SCRs prior to their selection of a card, while they pondered from w hich deck to choose, but no patients showed such anticipatory SCRs. Th e absence of anticipatory SCRs in patients with prefrontal damage is a correlate of their insensitivity to future outcomes. It is compatible with the idea that these patients fail to activate biasing signals th at would serve as value markers in the distinction between choices wit h good or bad future outcomes; that these signals also participate in the enhancement of attention and working memory relative to representa tions pertinent to the decision process; and that the signals hail fro m the bioregulatory machinery that sustains somatic homeostasis and ca n be expressed in emotion and feeling.