| Chapter 1:Attention bias of experimental pain persons and its effect on decision-makingObjectives:To determine whether experimental pain subjects had attention bias towards pain stimuli,and whether their behavioral decisions were affected by this bias.Methods:We recruited 40 healthy individuals,into whom were divided control group and experimental pain group.Capsaicin was sprayed on the inner forearm of the subjects to replicate pain symptoms.Data of behavior and event-related potentials from the subjects after high and low cognitive load tasks with pain and non-pain words as stimulus were acquired and analyzed.Results:In the event-related potentials(ERP)response to words,N1 and P2 waves were more obvious in the control group,with a significant difference between neutral words and other words,while P2 and N3 waves were obvious in the experimental pain group,with a significant difference between pain words and other words in P2 and a significant difference between neutral words and other words in N3.In the ERP response to task execution,there were no significant differences in the early components(N1,P2,N2 and the early part of the late positive potential)of the experimental pain group,while significant differences in the control group between different load tasks.Experimental pain subjects had a lower accuracy rate than control subjects.Pain persons and high cognitive load tasks showed a delay in the peak energy of Delta and Theta oscillations at FZ from 500-800ms after keyboard response.Conclusions:(1)Experimental pain subjects had priority in attention capture of pain words,which happened in an early time.(2)Decision-making in subjects were not affected by pain words but affected by pain.Peak of prefrontal oscillation of pain subjects or under high cognitive load tasks was delayed.Chapter 2:Effects of repetitive transcranial magnetic stimulation on left dorsolateral prefrontal lobe on pain and working memory in experimental pain personsObjectives:To determine whether high frequency repetitive transcranial magnetic stimulation of the left dorsolateral prefrontal lobe can relieve pain and improve working memory in experimental pain persons.Methods:Eighteen healthy individuals were recruited in this part.Experimental pain was induced by electrical stimulation,after which real or sham repetitive transcranial magnetic stimulation(rTMS)was carried on left dorsolateral prefrontal lobe(DLPFC).Pain scores at 0,20,40,and 60 minutes after stimulation and resting electroencephalogram(EEG)at 20,40,and 60 min were measured,with 0-back and 2-back tests recorded by EEG interspersed among.We compared pain scores at 0,20,40 and 60 minutes after stimulation to that before stimulation,and compared EEG oscillation changes at different time points,as well as effects of real and sham stimulation on working memory behavior and ERP components.Results:There was no statistical difference in pain scores among time before stimulation and multiple time-points after real and sham rTMS.Alpha and Beta oscillations of EEG were significantly different between groups 20 minutes after stimulation,but no significance was found between or among other time-points.Theta oscillation revealed no difference.There was no significant difference in cognitive behavior before and after stimulation,neither was there difference between real and sham rTMS.Pain scores decreased after n-back tasks compared with that before stimulation,but no different was found between different loads.Conclusions:(1)Single rTMS on the left DLPFC had no analgesic effect on experimental pain induced by electrical stimulation.(2)Single rTMS on left DLPFC can change the cerebral cortex excitability for no more than 40 minutes.(3)N-back task has analgesic effect on experimental pain induced by electrical stimulation. |
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