背外侧前额叶损伤患者跨时选择能力的研究

Study of intertemporal choice in patients with dorsolateral frontal cortex lesions

目的研究背外侧前额叶(d LPFC)损伤患者跨时选择能力的改变。方法采用跨时选择中文版实验范式对25例d LPFC损伤患者(d LPFC组)及与之相匹配的27名健康对照者(HC组)进行评测。结果与HC组比较,d LPFC组顺序数字广度、词汇流畅性测试评分显著降低,色字干扰实验时间显著升高(P<0.05~0.01),倒序数字广度评分差异无统计学意义(P>0.05)。在now条件下,d LPFC组时间较久-金额较大(LL)选择比率显著低于HC组(P<0.05);d LPFC组中金额差值LL选择比率显著低于HC组(P<0.05),两组间低金额差值及高金额差值LL选择比率差异无统计学意义(均P>0.05)。在not-now条件下,d LPFC组与HC组LL选择比率差异无统计学意义(P>0.05);两组间各金额差值选择LL的比率差异无统计学意义(均P>0.05)。d LPFC组和HC组LL选择比率与金额差值量级显著相关(F=26.615,P=0.000;F=21.683,P=0.000),与now或not-now无关(F=0.427,P=0.517;F=0.587,P=0.447)。采用相关性分析发现,d LPFC组中色字干扰实验时间与now条件下中金额差值组LL选择比率呈正相关(r=0.475,P=0.019)。结论d LPFC损伤患者跨时选择能力受损,提示d LPFC可能是参与跨时选择的重要脑结构。

Objective To investigate the ability of intertemporal choices in patients with dorsolateral frontal cortex （dLPFC） lesions. Methods Twenty five dLPFC damaged individuals and 27 healthy controls （HC） were investigated by intertemporal choice test. Results Compared with HC, the forward digital span and the verbal fluency test scores of dLPFC were decreased significantly, and the time of stroop test was increased significantly（P 〈 0. 05 - 0.01 ） , no group difference was observed in the backward digital span （ P 〉 0. 05 ）. The ratio of later-larger （LL） choice in dLPFC demonstrated significantly lower than that in HC for now trails（ P 〈 0. 05 ）, and the ratio in intermediate relative differences of reward magnitudes in dLPFC was significantly lower than that in HC （ P 〈 0. 05 ）. The contrasts of the ratio of LL in terms of small relative differences and large relative differences of reward magnitudes were non-significant （all P 〉 0.05 ）. The choices between two groups for not-now trails were non- significant, and the same as that for small, intermediate and large relative differences （ P 〉 0. 05 ） . The ratio of LL in dLPFC and HC both correlated with the magnitude of the reward difference significantly （ F = 26. 615, P = 0. 000 ; F = 21. 683, P = 0. 000）, not related to now or not-now trails （ F = 0. 427, P = 0. 517 ; F = 0. 587, P = 0. 447 ）. The Pearson correlation analysis showed that there was a positive correlation in dLPFC between the stroop test and the LL ratio of intermediate relative differences in reward magnitudes （ r = 0. 475, P = 0. 019 ）. Conclusion The ability of intertemporal choices in dLPFC patients has been impaired, demonstrating the dLPFC as a causal structure for intertemporal choice.