Hemodynamic and Light-Scattering Changes of Rat Spinal Cord and Primary Somatosensory Cortex in Response to Innocuous and Noxious Stimuli.
Hemodynamic and Light-Scattering Changes of Rat Spinal Cord and Primary Somatosensory Cortex in Response to Innocuous and Noxious Stimuli.
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DOI：
10.3390/brainsci5040400
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发表时间：
2015-09-29
期刊：
影响因子：
3.3
通讯作者：
Peng YB
中科院分区：
文献类型：
--
作者：
He JW;Liu H;Peng YB
神经成像技术具有卓越的空间分辨率和非侵入性，已成为评估动物和人类神经活动的有力工具。然而，神经影像学对疼痛的有效性仍然不清楚，部分原因是疼痛过程中的神经血管耦合没有完全表征。我们目前的工作旨在揭示疼痛过程中神经血管参数的模式。一种新的光纤方法被用来获得绝对值的区域氧（HbO）和脱氧血红蛋白浓度，氧饱和度（SO2），和光散射系数从脊髓和初级体感皮层（SI）在10只大鼠。在戊巴比妥麻醉下，对后肢施加短暂的机械和电刺激（范围从无害到有害强度）以及持久的有害刺激（福尔马林注射）。在脊髓和SI半球间的比较被用来确认感觉处理过程中的功能激活。我们发现，所有的神经血管参数显示刺激引起的变化，然而，变化的模式不同的区域和刺激。特别是，短暂增加的HbO和SO2更可靠地归因于短暂的刺激，而持续减少的SO2更可靠地归因于福尔马林。只有同侧的SI表现出延迟的反应，短暂的刺激。总之，无害和有害刺激在关键中心（例如，脊髓和SI）沿着躯体感觉通路;然而，没有单一的反应模式（如幅度，持续时间，偏侧，减少或增加），能够始终区分伤害性刺激。我们的研究结果强烈表明，神经血管反应模式之间的短暂和持久的伤害性刺激，也可以不同的脊髓和SI。因此，使用多参数策略定制的刺激方式（短暂或持久）以及区域依赖性的特点可能是更有效地检测疼痛使用神经成像技术。
Neuroimaging technologies with an exceptional spatial resolution and noninvasiveness have become a powerful tool for assessing neural activity in both animals and humans. However, the effectiveness of neuroimaging for pain remains unclear partly because the neurovascular coupling during pain processing is not completely characterized. Our current work aims to unravel patterns of neurovascular parameters in pain processing. A novel fiber-optic method was used to acquire absolute values of regional oxy- (HbO) and deoxy-hemoglobin concentrations, oxygen saturation rates (SO2), and the light-scattering coefficients from the spinal cord and primary somatosensory cortex (SI) in 10 rats. Brief mechanical and electrical stimuli (ranging from innocuous to noxious intensities) as well as a long-lasting noxious stimulus (formalin injection) were applied to the hindlimb under pentobarbital anesthesia. Interhemispheric comparisons in the spinal cord and SI were used to confirm functional activation during sensory processing. We found that all neurovascular parameters showed stimulation-induced changes; however, patterns of changes varied with regions and stimuli. Particularly, transient increases in HbO and SO2 were more reliably attributed to brief stimuli, whereas a sustained decrease in SO2 was more reliably attributed to formalin. Only the ipsilateral SI showed delayed responses to brief stimuli. In conclusion, innocuous and noxious stimuli induced significant neurovascular responses at critical centers (e.g., the spinal cord and SI) along the somatosensory pathway; however, there was no single response pattern (as measured by amplitude, duration, lateralization, decrease or increase) that was able to consistently differentiate noxious stimuli. Our results strongly suggested that the neurovascular response patterns differ between brief and long-lasting noxious stimuli, and can also differ between the spinal cord and SI. Therefore, a use of multiple-parameter strategy tailored by stimulus modality (brief or long-lasting) as well as region-dependent characteristics may be more effective in detecting pain using neuroimaging technologies.