Floden D, Alexander M P, Kubu C S, Katz D, Stuss D T
Rotman Research Institute, Baycrest, Toronto, Ontario, Canada.
Neuropsychologia. 2008 Jan 15;46(1):213-23. doi: 10.1016/j.neuropsychologia.2007.07.020. Epub 2007 Aug 3.
Frontal lobe dysfunction may underlie excessively impulsive and risky behavior observed in a range of neurological disorders. We devised a gambling task to examine these behavior tendencies in a sample of patients who had sustained focal damage to the frontal lobes or nonfrontal cortical regions as well as in a matched sample of healthy control subjects. The main objectives of the study were: (1) to behaviorally dissociate impulsivity and risk-taking; (2) to examine potential associations between specific frontal lesion sites and impulsivity or risk-taking; (3) to investigate the influence of reinforcement and trial timing on both behaviors. Our results indicated that patients and controls were equally likely to perform impulsively. Risk-taking performance strategies, however, were related to left ventrolateral and orbital lesion sites. Moreover, risk-taking was also associated with blunted response alteration following a nonrewarded trial. Patients and control subjects showed identical responses to reward-timing manipulations consistent with formal decision-making theory. These findings suggest that ventrolateral and orbital lesions are related to the reward-based aspects of decision-making (risk-taking) rather than to simple response disinhibition (impulsivity). Reduced reaction to the negative consequences of one's actions may underlie this behavior pattern.
额叶功能障碍可能是一系列神经疾病中出现的过度冲动和冒险行为的潜在原因。我们设计了一项赌博任务，以在额叶或非额叶皮质区域遭受局灶性损伤的患者样本以及匹配的健康对照受试者样本中检查这些行为倾向。该研究的主要目标是：（1）从行为上区分冲动性和冒险行为；（2）检查特定额叶病变部位与冲动性或冒险行为之间的潜在关联；（3）研究强化和试验时机对这两种行为的影响。我们的结果表明，患者和对照组冲动行事的可能性相同。然而，冒险行为的表现策略与左侧腹外侧和眶部病变部位有关。此外，冒险行为还与无奖励试验后的反应改变迟钝有关。患者和对照受试者对奖励时机操纵的反应相同，这与正式决策理论一致。这些发现表明，腹外侧和眶部病变与基于奖励的决策方面（冒险行为）有关，而不是与简单的反应抑制解除（冲动性）有关。对自己行为的负面后果反应降低可能是这种行为模式的基础。
