An ERP study on attention bias in experimental pain individuals under different cognitive loads.
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Purpose: The aim of the present study was to investigate the behavioral and electrophysiological differences between experimental pain persons and healthy controls when conducting attention bias task under different cognitive load conditions. Methods: 30 healthy subjects were recruited from the Southern medical university of China, into which equally divided the experimental pain group and healthy control group (7 female/15 and 8 female /15; mean age ± SD: 22.53±2.35 and 21.69±3.25 respectively; mean years of education ± SD:16.30 ±3.58 and 15.78 ±3.65 respectively). All subjects underwent ERP examination when completing an attention bias task. The experimental pain subjects simulated pain by spraying capsaicin on the inner side of the upper arm with an average pain score of 6.08±2.33. Healthy control group reported no pain. Results: Behavioral results showed that the main effect of load was significant, with a longer respond time and lower correct rate under high cognitive load compared with low one, suggesting that the task we used could well distinguish different loads. Further ERP results revealed that the main effect of wave peaks (N1 and P2) between groups was significant. Experimental pain subjects responded to all word interferences with a smaller amplitude than that of the normal group. A significantly synergistic effect of interference word * load, with a significantly smaller amplitude induced by pain words and negative words of early components P2 and N3 under the condition of high cognitive load, and interference word*group, with a smaller amplitude of N1 and N3 elicited by various interference words, were found. Conclusion: Experimental pain subjects’ response to the words of external stimulus was weakened as a result of the disturbance of pain. We believed that cognitive load mainly affected and regulated the early components of attention, that the processing mode of interference words (especially pain words and negative words) was different under high cognitive load compared with low one, which could provid electrophysiological evidence for cognitive load theory.