The Effects Of Self-initiated Tactile Sensationand Combination Of Stimulations On The Analgesic Effect Of Transcutaneous Electrical Nerve Stimulation And The Underlying Mechanism

Transcutaneous electrical nerve stimulation(TENS)has been proved have analgesic effect in theoreticaland clinic research.TENS has achieved good curative effect in many clinical pain treatments since the 1970 s when it began to be applied in clinical application.For instance,TENS has played an important role in reducing postoperative pain,chronic pain,dysmenorrhea and childbirth pain and other painful diseases.The analgesic effect of TENS is influenced by many factors.A major of studies have proved that many factors,such as the placement of TENS electrodes,pulse parameters(including the intensity of electric current,current frequency,pulse width,treatment time and period),individual differences,will influence the analgesic effect of TENS.In addition to the above factors,the researchers have found that combining electroacupuncture stimuli with different parameters can have a better analgesic effect,and that the way how to combinewill affect the analgesic effect.Wefirst combine the tactile stimuli and pain stimulitogether in two different ways to explore which has the better analgesia effectin the first experiment of this study.In addition,it is well-known that sensory perception can be attenuated when sensorystimuli are initiated by self-actions.This phenomenon is explained by the consistency between forwardmodels of anticipatedaction effects and actual sensory feedback.Specifically,the brainstate related to the binding between motorprocessingand sensory IV perception would execute inhibitory function by gating sensory information via top-down control.Since the brain state could casuallyinfluence the perception of subsequent stimuliof different sensory modalities,we hypothesize that pain evoked by nociceptive stimulifollowing the self-initiated tactile stimulation would be attenuated as compared to that following externally-determined tactile stimulation.In the second this experiment of study,wecomparedthe analgesic effect of TENS between the conditionthatinitiation of TENS is controlled by the patients themselves and the conditionthat initiation of TENS is controlled by the external environment.In the first experiment,wecompareanalgesia effect of TENSin two different ways:(1)the stimulation of the two frequency wave(4Hz and 100Hz)is delivered via a pair of electrodes alternately(dilatational wave);(2)the stimulation of the two frequency wave(4Hz and 100Hz)is delivered viatwo pairs of electrodes at the same time(simultaneous wave).The results show that there is no significant difference of analgesic effect of TENS in these two combinations.The experiment results are not in line with the previous research.The possible reasons in this study maybe that the combinations of the tactile stimuli and pain stimuliare not consistent with the combination in previous studies where researchers use the combination of electroacupuncturestimuli.In addition,we use people as the experiment subjects,which isn't consistent with the previous study in which researchers use the mice as experimental objects.The experiment doesn't have statistically significance;however,we can presentthe tendency that the analgesic effect of dilatational wave was superior to that of simultaneous wavein a pointview of descriptive statistical.Thistendencyis not significant in statisticsbythe reason of lack of participants.So we can carry out the future research viaincreasingamount of the subjects to researchthe analgesic effect of two kinds of combination way.In the second experiment,wecomparepsychophysicaland neurophysiological responses to identical nociceptive-specificlaserstimuli in twodifferent conditions: Self-initiated Tactile Sensation condition(STS)and Non Self-initiated Tactile Sensation condition(N-STS).We observed that pain intensity and unpleasantness,as well as laser evoked brain responses,were significantly reduced in the STS condition than in the N-STS condition.In addition,magnitudes of alpha and beta oscillations prior to laser onset were significantly larger in the STS condition than in the N-STS condition.These results confirmed that pain perception and pain related brain responses wereattenuated when the tactile stimulation was initiated by subjects' voluntary actions,and exploited neural oscillations reflecting the binding between motor processing and sensory feedback.Thus,our study elaboratedour understanding of underlying neural mechanisms related to top-down modulations of the analgesic effect induced by self-initiated tactile sensation,which provided theoretical basis to improve the analgesic effect in various clinical applications.