伤害性刺激诱发体感皮层单位放电的互协方差函数分析

ANALYSIS OF NOCICEPTIVE EVOKED DISCHARGES IN SOMATOSENSORY CORTEX BY NORMALIZED CROSS-COVARIANCE FUNCTION

用伤害性刺激猫的腓浅神经（ＰＮ）诱发体感皮层Ⅰ区（ＳⅠ）单位放电（ＥＤ），以放电阵列图和标准化互协方差函数进行定量分析。结果显示，用２５Ｖ刺激时引起Ａ类和Ｃ类纤维传入，在ＳⅠ记录到潜伏期为１４．８±５．０ｍｓ的早期ＥＤ（Ｅ），与用３Ｖ弱刺激ＰＮ时只引起单纯Ａ类纤维传入引起的放电反应比较，潜伏期无显著区别。用极化电流阻断Ａ类纤维传入后，单纯Ｃ类传入只引起潜伏期为２２２．６±２８．７ｍｓ的晚期ＥＤ（Ｌ）或１２９．２４±２３ｍｓ的中期ＥＤ（Ｍ），Ｍ、Ｌ可相互抑制，也可被Ａ类纤维传入所抑制。静脉注射镇痛剂吗啡后，Ｍ和Ｌ显著减少，Ｅ变化不显著。提示Ｃ类纤维传入可能分两类分别到达ＳⅠ区引起两种不同潜伏期的诱发放电，均与疼痛关系密切，都可作为慢痛反应的指标。

Normalized cross-covariance function(NCCVF) of the unit discharges elicited by noxiousstimulation of superficial peroneal nerve(PN) showed an obvious early spike train(E)with shortlatency.After blockade of A-fiber by a polarizing current nociceptive stimulation evoked a latespike train(L)with long latency and E disappeared. When the intensity of blocking current in-creased further to some extent,L disappeared and a spike train with moderate latency(M)occur-red.It was suggested that A-fiber input elicited E and C-fiber input elicited M and L,and thatM and L might be depressed by A-fiber input,and they might interact each other.Afterintravenous injection of morphine M and L were inhibited more obviously than E.It was sug-gested that L and M might be associated with pain perception.