Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, North Carolina.
Department of Neuroscience, University of Florida College of Medicine, Gainesville, Florida.
J Pain. 2019 Apr;20(4):405-419. doi: 10.1016/j.jpain.2018.08.009. Epub 2018 Sep 15.
Traditionally, cytoarchitectonic area 3a of primary somatosensory cortex (SI) has been regarded as a proprioceptive relay to motor cortex. However, neuronal spike-train recordings and optical intrinsic signal imaging, obtained from nonhuman sensorimotor cortex, show that neuronal activity in some of the cortical columns in area 3a can be readily triggered by a C-nociceptor afferent drive. These findings indicate that area 3a is a critical link in cerebral cortical encoding of secondary/slow pain. Also, area 3a contributes to abnormal pain processing in the presence of activity-dependent reversal of gamma-aminobutyric acid A receptor-mediated inhibition. Accordingly, abnormal processing within area 3a may contribute mechanistically to generation of clinical pain conditions. PERSPECTIVE: Optical imaging and neurophysiological mapping of area 3a of SI has revealed substantial driving from unmyelinated cutaneous nociceptors, complementing input to areas 3b and 1 of SI from myelinated nociceptors and non-nociceptors. These and related findings force a reconsideration of mechanisms for SI processing of pain.
传统上，初级躯体感觉皮层（SI）的细胞构筑学区域 3a 被认为是运动皮层的本体感受中继。然而，从非人类感觉运动皮层获得的神经元尖峰活动记录和光内信号成像显示，区域 3a 中的一些皮层柱中的神经元活动可以很容易地被 C 伤害感受器传入驱动触发。这些发现表明，区域 3a 是大脑皮层对二级/缓慢疼痛编码的关键环节。此外，在γ-氨基丁酸 A 受体介导的抑制作用的活性依赖性反转存在的情况下，区域 3a 有助于异常疼痛处理。因此，区域 3a 内的异常处理可能从机械上导致临床疼痛状况的产生。观点：对 SI 的区域 3a 的光学成像和神经生理学映射显示，来自无髓鞘皮肤伤害感受器的大量驱动，补充了来自有髓鞘伤害感受器和非伤害感受器的对 SI 的区域 3b 和 1 的输入。这些和相关的发现迫使人们重新考虑 SI 处理疼痛的机制。
