Study Of EEG Underlying The Effect Of Chronic Pain On Decision Making

Chronic pain affects patients’life quality and induces psychological disorders such as depression and anxiety, and other symptoms, severely impairing the patient’s physical and mental health. Moreover, chronic pain also has adverse effects on patient’s cognitive ability. A large number of studies have reported that chronic pain would impair the ability of decision-making, which is one of the most advanced cognitive functions of human being. However, the neural mechanism underlies the impact of chronic pain on decision-making-related feedback is still largely unknown.In the present study, electroencephalogram (EEG) signal with high temporal resolution were recorded from chronic pain patients (n=13) and healthy subjects (control group, n=12) while they were performing a Iowa gambling task, and compared with each other. Firstly, all subjects were asked to finish Wechsler Intelligence Scale and a Stroop task, In the following Iowa gambling task, subjects were required to choose cards from four card decks with different loss or win results to make their maximum benefits in three sessions (two runs in one session).The behavioral results showed that, as for healthy volunteers, the number of choices for good decks was significantly higher than the number of choices for bad ones (p<0.05), which is in consist with the finding from previous studies. However, chronic pain patients did not show a significant difference among the number of choices from four decks, indicating that they failed to learn right strategy for choosing cards. In addition, in Stroop color-word conflict test, the correct response in chronic pain patients was found significantly less than that in healthy controls (p<0.05), suggesting abnormal cognitive control in chronic pain group.The electrophysiological analyses focused on three feedback potentials:P200, FRN (Feedback-Related Negativity) and P300. Results showed that,1) amplitude of P200 had no significant difference between two groups among all three sessions (p>0.1); 2) as for patient group, the FRN of choosing disadvantageous cards was significantly higher than FRN of choosing advantageous card during the second session (p<0.05), indicating that abnormality of decision-making may lead to more violation of the expectations for disadvantageous choices; 3) P300 on the healthy volunteers showed a significant difference between advantageous and disadvantageous cards during the first session (p<0.01), while the patients displayed the same significant difference during the second session (p<0.05) which may imply that patients have difficult in achieving the goal because of their impairment in cognitive resource allocation.The present study explores the behavioral results and EEG activities of chronic pain patients while they were perforing a Iowa gambling task. Our study sheds some light on the neural mechanism of impaired decision-making in chronic pain patients, providing evidence for elucidating the exact cause of abnormal decision making in chronic pain patients and for exploration of potential treatment.