Program in Neuroscience, University of Maryland School of Medicine, 20 Penn St., Baltimore, MD 21201, USA.
J Neurophysiol. 2010 Sep;104(3):1717-25. doi: 10.1152/jn.00161.2010. Epub 2010 Jul 21.
Central pain syndrome (CPS) is a debilitating and chronic pain condition that results from a lesion or dysfunction in the CNS. The pathophysiological mechanisms underlying CPS are poorly understood. We recently demonstrated that CPS is associated with suppressed inputs from the inhibitory nucleus zona incerta to the posterior thalamus (PO). As a consequence, activity in PO is abnormally increased in CPS. Because the perception of pain requires activity in the cerebral cortex, CPS must also involve abnormal cortical activity. Here we test the hypothesis that CPS is associated with increased activity in the primary somatosensory cortex (SI), a major projection target of PO that plays an important role in processing sensory-discriminative aspects of pain. We recorded activity of single units in SI in rats with CPS resulting from spinal cord lesions. Consistent with our hypothesis, SI neurons recorded from lesioned rats exhibited significantly higher spontaneous firing rates and greater responses evoked by innocuous and noxious mechanical stimulation of the hindpaw compared with control rats. Neurons from lesioned rats also showed a greater tendency than controls to fire bursts of action potentials in response to noxious stimuli. Thus, the excruciatingly painful symptoms of CPS may result, at least in part, from abnormally increased activity in SI.
中枢痛综合征（CPS）是一种由中枢神经系统损伤或功能障碍引起的使人虚弱的慢性疼痛病症。CPS 的病理生理机制尚未被完全理解。我们最近的研究表明，CPS 与抑制性核团缰核对后丘脑（PO）的抑制性传入减少有关。因此，CPS 患者的 PO 活动异常增加。由于疼痛的感知需要大脑皮层的活动，CPS 也必须涉及异常的皮层活动。在这里，我们验证了这样一个假设，即 CPS 与初级体感皮层（SI）的活动增加有关，PO 的主要投射靶标 SI 在处理疼痛的感觉辨别方面起着重要作用。我们记录了脊髓损伤导致 CPS 的大鼠的 SI 中的单个神经元的活动。与我们的假设一致，与对照组大鼠相比，损伤大鼠的 SI 神经元表现出更高的自发性放电率，对后足的无害和有害机械刺激的反应也更大。与对照组相比，损伤大鼠的神经元在受到有害刺激时也更倾向于爆发动作电位。因此，CPS 令人难以忍受的疼痛症状可能至少部分是由于 SI 中异常增加的活动引起的。
