Bechara A, Tranel D, Damasio H, Damasio A R
Department of Neurology, University of Iowa College of Medicine, Iowa City 52242, USA.
Cereb Cortex. 1996 Mar-Apr;6(2):215-25. doi: 10.1093/cercor/6.2.215.
Following damage to specific sectors of the prefrontal cortex, humans develop a defect in real-life decision making, in spite of otherwise normal intellectual performance. The patients so affected may even realize the consequences of their actions but fail to act accordingly, thus appearing oblivious to the future. The neural basis of this defect has resisted explanation. Here we identify a physiological correlate for the defect and discuss its possible significance. We measured the skin 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 uncertainty, rewards, and penalties. Both patients and controls generated SCRs after selecting cards that were followed by penalties or by reward. However, after a number of trials, controls also began to generate SCRs prior to their selection of a card, while they pondered from which deck to choose, but no patients showed such anticipatory SCRs. The 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 that would serve as value markers in the distinction between choices with good or bad future outcomes; that these signals also participate in the enhancement of attention and working memory relative to representations pertinent to the decision process; and that the signals hail from the bioregulatory machinery that sustains somatic homeostasis and can be expressed in emotion and feeling.
前额叶皮质特定区域受损后，尽管智力表现正常，但人类在现实生活决策中会出现缺陷。受影响的患者甚至可能意识到自己行为的后果，却未能相应地采取行动，因此似乎对未来漠不关心。这种缺陷的神经基础一直难以解释。在此，我们确定了该缺陷的一种生理关联，并讨论了其可能的意义。我们在一项新任务（一种纸牌游戏，该游戏通过纳入不确定性、奖励和惩罚因素来模拟现实生活决策）的执行过程中，测量了7名前额叶受损患者和12名正常对照者的皮肤电导反应（SCR）。患者和对照者在选择了会带来惩罚或奖励的纸牌后都会产生SCR。然而，经过多次试验后，对照者在思考从哪叠纸牌中选择时，也开始在选择纸牌之前就产生SCR，但没有患者表现出这种预期性SCR。前额叶受损患者缺乏预期性SCR与他们对未来结果不敏感相关。这与以下观点相符：这些患者无法激活偏向信号，而这些信号在区分具有好坏未来结果的选择时可作为价值标记；这些信号还参与相对于与决策过程相关表征的注意力增强和工作记忆增强；并且这些信号来自维持躯体稳态的生物调节机制，并可在情绪和感觉中表现出来。
