Intertemporal Choice In Patients With Dorsolateral Frontal Cortex Lesions

Background:Intertemporal choices are decisions with consequences in multiple time periods and constitute a significant part of social cognition.The neural mechanism of intertemporal choice is complex.The relationship of prefrontal cortex and the ability of intertemporal choice is mainly based on experiments about animals,functional neuroimaging and transcranial magnetic stimulation.The object in this study were patients with brain damage.The study can be used to further explore the neural mechanism of intertemporal choice,and to provide the evidence for the pathogenesis of relevant neuropsychiatric disorders.Objective: To investigate the ability of intertemporal choice in patients with dorsolateral prefrontal cortex(dLPFC)lesions.To further explore the role of the dLPFC in intertemporal choice.Method: Twenty five dLPFC damaged patients and twenty seven healthy controls(HC) were investigated by Intertemporal choice Test.All participants received a battery of cognitive neuropsychological test assessment.Results: Compared with HC,the forward digital span and the VFT scores of dLPFC were decreased significantly,and the time of Stroop test was increased significantly(P<0.05).No group difference was observed in MMSE,HAMA,HAMD and the backward digital span.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 and large relative differences of reward magnitudes were non-significant(both 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).No differences were observed for the valuation task between two groups across the different levels.Conclusion: The ability of intertemporal choices in dLPFC patients has been impaired.DLPFC patients prefer impulsive decisions,while the subjective value was not significantly different from that of HC.The results demonstrated the dLPFC was a causal structure for intertemporal choice.The possible mechanism is the participation of dLPFC in the process of self control in intertemporal choices.