Nociceptive afferent activity alters the SI RA neuron response to mechanical skin stimulation.
Nociceptive afferent activity alters the SI RA neuron response to mechanical skin stimulation.
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DOI：
10.1093/cercor/bhq039
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发表时间：
2010-12
期刊：
影响因子：
3.7
通讯作者：
B. Whitsel;O. Favorov;Yongbiao Li;Jaekwang Lee;P. Quibrera;M. Tommerdahl
中科院分区：
文献类型：
--
作者：
B. Whitsel;O. Favorov;Yongbiao Li;Jaekwang Lee;P. Quibrera;M. Tommerdahl
研究表明，当刺激幅度“接近阈值”（即10-50 μm）时，松鼠猴初级体感皮层（SI） 3b/1区快速适应（RA）神经元对感受野中心（RF（中心））的25 hz刺激的平均脉冲放电率（MFR）和程度降低，从而可靠地引起人类皮肤疼痛（即，与47-51°C探针接触5-7秒，皮内注射糖原）。相比之下，当25-Hz刺激幅度为100-200 μm（阈上）时，47-51°C接触或皮内注射氧原对RA神经元MFR和夹带没有影响或增强。该结果归因于γ-氨基丁酸（GABA）作用于RA神经元GABA(A)受体的“活性依赖性”。由47-51°C探针或皮内刺痛觉触发的伤害性传入驱动激活3a区伤害反应神经元，该神经元通过皮质-皮质连接，导致3b/1区释放GABA。假设当RA神经元活动较低时（如RF（中心）刺激较弱/接近阈值时），GABA呈超极化/抑制性并抑制刺激诱发的RA神经元MFR和夹带，但当RA神经元活动较高时（当刺激较强/超过阈值时），GABA呈去极化/兴奋性并增强MFR和夹带。
Procedures that reliably evoke cutaneous pain in humans (i.e., 5-7 s skin contact with a 47-51 °C probe, intradermal algogen injection) are shown to decrease the mean spike firing rate (MFR) and degree to which the rapidly adapting (RA) neurons in areas 3b/1 of squirrel monkey primary somatosensory cortex (SI) entrain to a 25-Hz stimulus to the receptive field center (RF(center)) when stimulus amplitude is "near-threshold" (i.e., 10-50 μm). In contrast, RA neuron MFR and entrainment are either unaffected or enhanced by 47-51 °C contact or intradermal algogen injection when the amplitude of 25-Hz stimulation is 100-200 μm (suprathreshold). The results are attributed to an "activity dependence" of γ-aminobutyric acid (GABA) action on the GABA(A) receptors of RA neurons. The nociceptive afferent drive triggered by skin contact with a 47-51 °C probe or intradermal algogen is proposed to activate nociresponsive neurons in area 3a which, via corticocortical connections, leads to the release of GABA in areas 3b/1. It is hypothesized that GABA is hyperpolarizing/inhibitory and suppresses stimulus-evoked RA neuron MFR and entrainment whenever RA neuron activity is low (as when the RF(center) stimulus is weak/near-threshold) but is depolarizing/excitatory and augments MFR and entrainment when RA neuron activity is high (when the stimulus is strong/suprathreshold).