机械伤害刺激激活丘脑-皮层神经网络的多通道记录研究

目的:在清醒大鼠脑内同步记录内、外侧痛觉传导通路神经元的伤害性活动,在丘脑-皮层水平观察各脑区的编码模式以及脑区之间的功能联系.方法:麻醉状态下在动物丘脑和皮层的四个区域单侧植入微电极阵列,在清醒状态下给予伤害和非伤害性机械刺激,同步记录多个神经元的单位电活动,并利用滑行窗口分析、交互相关分析、聚类分析以及判别分析等运算方法进行信息提取.结果:在7只大鼠上共记录到180个神经元的单位电活动.伤害和非伤害机械刺激均引起以兴奋为主的反应.与非伤害刺激相比,伤害性刺激使各脑区神经元反应比例显著增加,平均反应强度显著增加,两条通路上脑区之间的相关性亦显著增加.另外,从神经元群体编码的角度看,内侧通路对伤害与非伤害机械刺激的分辨能力稍优于外侧通路.结论:中枢对伤害性机械刺激的编码有赖于多个脑区的共同参与,内、外侧系统对刺激的编码能力不同,可能与刺激本身的特性有关.

THE ACTIVATION OF THALAMO-CORTICAL NEURAL NETWORK BY NOXIOUS MECHANICAL STIMULATION: A MULTICHANNEL RECORDING STUDY

Objective: To simultaneously record the nociceptive neuronal activity within medial and lateral pain pathways in awake rats,and explore the nociceptive coding patterns and functional connections at thalamo-cortical level.Methods: Rats were anesthetized and mounted on a stereotaxic apparatus.Four microarrays were implanted unilaterally into the target thalamic and cortical areas.Simultaneous recording of thalamo-cortical single neurons was obtained in the awake state during the delivery of noxious or innocuous stimuli.Analysis methods involved sliding-window technique,cross-correlation computation,cluster analysis and discriminant analysis.Results: A total of 180 single neurons were detected in seven rats.Both noxious and innocuous mechanical stimuli induced predominantly excitatory responses within recorded areas.The painful stimuli gave rise to higher response intensity,larger percentage of responding neurons,and stronger inter-regional cross-correlations compared to nonpainful stimuli.Furthermore,by comparison of neural ensemble performance discriminating painful from nonpainful mechanical stimuli,it seemed that the discrimination capability of medial system was somehow better than lateral system.Conclusion: The central nervous encoding of nociception depends on the extensive activation of multiple brain regions.The discrimination capability of medial versus lateral system was different,which may be related to the property of stimulation per se.