Centre for Functional Magnetic Resonance Imaging of the Brain, Nuffield Department of Clinical Neurosciences, Nuffield Division of Anaesthetics, University of Oxford, Oxford OX3 9DU, UK.
J Neurosci. 2012 May 2;32(18):6231-9. doi: 10.1523/JNEUROSCI.2543-11.2012.
Chronic pain is thought to arise because of maladaptive changes occurring within the peripheral nervous system and CNS. The transition from acute to chronic pain is known to involve the spinal cord (Woolf and Salter, 2000). Therefore, to investigate altered human spinal cord function and translate results obtained from other species, a noninvasive neuroimaging technique is desirable. We have investigated the functional response in the cervical spinal cord of 18 healthy human subjects (aged 22-40 years) to noxious thermal and non-noxious tactile stimulation of the left and right forearms. Physiological noise, which is a significant source of signal variability in the spinal cord, was accounted for in the general linear model. Group analysis, performed using a mixed-effects model, revealed distinct regions of activity that were dependent on both the side and the type of stimulation. In particular, thermal stimulation on the medial aspect of the wrist produced activity within the C6/C5 segment ipsilateral to the side of stimulation. Similar to data recorded in animals (Fitzgerald, 1982), painful thermal stimuli produced increased ipsilateral and decreased contralateral blood flow, which may reflect, respectively, excitatory and inhibitory processes. Nonpainful punctate stimulation of the thenar eminence provoked more diffuse activity but was still ipsilateral to the side of stimulation. These results present the first noninvasive evidence for a lateralized response to noxious and non-noxious stimuli in the human spinal cord. The development of these techniques opens the path to understanding, at a subject-specific level, central sensitization processes that contribute to chronic pain states.
慢性疼痛被认为是由于周围神经系统和中枢神经系统发生适应性变化而产生的。从急性疼痛到慢性疼痛的转变已知涉及脊髓（Woolf 和 Salter，2000）。因此，为了研究改变的人类脊髓功能并将从其他物种获得的结果转化，需要一种非侵入性的神经影像学技术。我们已经研究了 18 名健康人类受试者（年龄 22-40 岁）对左侧和右侧前臂的有害热和非有害触觉刺激的颈脊髓的功能反应。生理噪声是脊髓信号可变性的重要来源，在一般线性模型中进行了说明。使用混合效应模型进行的组分析揭示了依赖于刺激侧和刺激类型的活动的不同区域。特别是，手腕内侧的热刺激在同侧刺激侧的 C6/C5 节段内产生了活性。与在动物中记录的数据（Fitzgerald，1982）相似，疼痛的热刺激产生了同侧增加和对侧减少的血流，这可能分别反映了兴奋性和抑制性过程。对大鱼际的点状非疼痛刺激引起了更弥散的活动，但仍与刺激侧同侧。这些结果首次提供了在人类脊髓中对有害和无害刺激的偏侧反应的非侵入性证据。这些技术的发展为在特定于个体的水平上理解导致慢性疼痛状态的中枢敏化过程开辟了道路。
