The Effects Of Physiological And Social Pain On The Brain Potentials Of Reward-processing

Pain elicits the desire for a reward in order to alleviate the unpleasant feeling and it might be a consequence of facilitated neural activities in the reward circuit.However,reward processing is a dynamic process that can be divided into reward anticipation and reward experience,and the temporal modulation of pain on reward processing remains unclear.Social pain,a new concept has been put forward in the field of social cognition,refers to the painful experience caused by the breakdown of social relationships or the devaluation of social values,and shares similar neural processing with physiological pain.Does it have the same impact on reward processing with physiological pain? Or have its specific effect? A total of 3 EEG experiments were designed in our study to answer above questions.Experiment 1 explored the effect of physiological pain on monetary reward processing.61 subjects were recruited to complete a simple gambling task in painful or control condition and EEG signal was recorded during the whole process.The results show that pain increased the activities of experience-related P300 and delta oscillation in later reward processing,but did not affect the activities of FRN and theta,which are responsible for early reward detection.These results indicated that physiological pain enhanced the experience of monetary reward.Experiment 2 explored how social pain affect monetary reward processing.Results show that pain reduced the activities of P300 and theta oscillation for loss feedback.However,no significant effect of social pain was found on the process of reward feedback due to the ceiling effect possibly.It was found that social pain would significantly reduce the brain activity of reward processing combined the data of experiments 2 and 3.A trend of decreased activity was observed in the experiment,which indicated that social pain may weaken the processing process of monetary rewards.Experiment 3 explored the effect of social pain on social reward processing.44 subjects were recruited to complete a social evaluation task after cyberball game.Results show that social pain reduced the activities of anticipation-related SPN、experience-related P300、delta and theta oscillations.These implied that social pain weakened both the anticipation and experience of social reward.All in all,this study found that both physiological pain and social pain affect reward processing.In addition,the effect of physiological pain on reward processing is mainly to enhance and promote this reward processes,while the effect of social pain is more to weaken and inhibit it.Analyzing based on the fear-avoidance theory model,avoidance behavior under social pain is likely to be caused by perceived threat from social rejection.We could assume that human beings,as social animals,may have a fear response to threat signals related to social information,thus showing more avoidance and inhibition behavior under social pain.