Contextual Factors Modulate Neural Response To Others Pain

Observing other in pain triggers the empathic responses,which involve two temporal stages of processing: an early,automatic processing that result in emotional contagion and affective sharing,and a later,cognitively controlled process related to emotional regulation.Previous studies suggest that this neural response can be modulated by numerous factors.In this essay,three major factors(the pain-taker,the observer and the contextual factor)were summarized in the background section.Almost every individual has to deal with other’s emotions with concurrent cognitive task or fluctuate mood in everyday life.Hence,it’s important to explore how working memory load and the observer’s current mood can influence empathy for pain.To explore how other’s pain is processed under different contextual terms seems to be meaningful both theoretically and practically.In Exp 1,we investigated how different levels of working memory load can influence the processing of task-irrelevant stimuli showing other’s pain.Twenty-two healthy subjects(eleven males)participated in this 2×2 within-subject designed experiment(mean age 20±2.4y).We manipulated WM load by requiring participants to memorize two(low WM load)or six(high WM load)digits at the beginning of each trial.Then picture depicting a person’s hands/forearms/feet in painful or non-painful situations was presented as a distractor.The participants were informed that these pictures were task-irrelevant and they should focus on memorizing the digits and they were required to judge if a given set of digits was the same as the one they saw at the beginning of the trial after the presentation of the picture.EEG during the observation of pictures under different WM loads was recorded by a 64-channel amplifier using a standard 10-20 system(Brain Products).The ERP results revealed that the WM load can influence the early automatic component P2 and N2.Comparing to low WM load,in the high WM-load condition,the painful pictures elicited significantly larger amplitudes in P2 and more negative amplitudes in N2 than the nonpainful pictures.Meanwhile,under the low WM-load conditions,there was no significant difference between the painful and non-painful pictures.This result showed that the WM load mainly influence the early automatic stage of processing in empathy for pain.Our findings indicate that other’s pain attracts greater attention and can be better processed when the cognitive control resources were depleted(i.e.,under high,relative to low,concurrent WM load).Under high WM load,enhanced emotional sharing and affective arousal level was reflected in the effect observed on P2 and N2.In Exp 2,we explored the time course of processing other’s pain under induced happy and sad moods.ERPs were recorded while participants observing pictures showing other’s in painful or non-painful conditions.Mood induction procedures were applied to the participants before observing the pictures.Happy and sad mood were induced by listening to about 10 minutes of music excerpts selected from the Chinese Affective Music System(CAMS).The ERP results revealed that the induced mood can influence the early automatic components N1 and N2 but not the later cognitive components P3 and LPP.Comparing to sad mood,happy mood suppressed the affective arousal and emotional sharing with other’s pain.These findings offer the first psychophysical evidence that people’s affective states can influence the empathic response to other’s pain.