人们早已知道

电针穴位可以在大脑皮层体感区引起诱发电位

据此许多研究者相信

针感的产生和大脑皮层有密切关系。近年来的研究进一步表明

皮层体感区(SⅠ区和 SⅡ区)对许多皮层下核团中神经元的伤害性反应具有下行调制作用。有的作者指出

针刺穴位激活皮层神经元

Single SI cortical neurons were recorded extracellularly with glass micro- pipettes

and their response properties to electro-acupuncture (EA)of contra- lateral Tsusanli (St.36)and Fenglung (St.40)

or to manual acupuncture (MA)of Tsusanli were observed in unanesthetized and paralyzed rats. In 46 rats

a total of 474 neurons were isolated in the hindlimb repre- sentation area of SI cortex.Among these neurons

228 responded to peripheral mechanical stimulation

and could be classified as cutaneous neurons

deep neurons and cutaneous-deep convergent neurons.Thirty five of them were identified as nociceptive neurons. Neurons of various sensory neurons and with receptive fields (RFs)located in the contralateral hindlimb responded to EA.Significant difference (P< 0.01)existed between the stimulation thresholds of cutaneous neurons (2.39± 0.27V)and those of deep neurons (4.12±0.48V).There was no significant difference between the thresholds of nociceptive and non-nociceptive neurons. The typical response of SI neurosis to single EA stimulation consisted of early discharges with a latency of 11.57±0.39msec and late train discharges with a latency of 54.79±4.07msec.A period of inhibition frequently inter- vened between the two groups of discharges.In a small portion of neurons

only a period of inhibition was prodnced.The responsiveness of neurons decreased markedly when the frequency of repeated EA stimulation was incre ased from 1Hz to 50Hz. Neurons of various sensory modalities responded to MA as well.Judging by RF distribution of the responsive neurons

however

the extent of action of MA was smaller than that of EA.Moreover

the responses to EA and MA were in opposite directions (excitation vs.inhibition)in a few neurons. Combined with the studies of others

the present work suggests that the activity of deep neurons in SI cortex

including muscle neurons and nocice- ptive neurons

are probably concerned with the production of needling sensa- tion during acupuncture.