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痛觉和痒觉信息的编码是科学家们几十年来极度关注和讨论的话题。然而,目前的编码理论(包括:强度学说、特异性学说和选择性学说)都无法解释实验中的所有现象。为了阐明疼痛和瘙痒产生的机制,研究者在脊髓中特异性地标记了一类中间神经元(胃泌素释放肽gastrin-releasing peptide,Gr P)Grp~+神经元,他们在研究了这些中间神经元的功能和特性后,提出了痛觉和痒觉编码的“Leaky Gate(门控泄漏)”模型。该模型的主要内容:脊髓节段存在一类Grp~+中间神经元,该神经元直接接受来自初级感觉神经元的痛觉和痒觉信息的突触传入,Grp~+神经元对痛觉和痒觉刺激的反应表现出不同特性,该类神经元只传导痒和弱痛的信号,在强痛刺激情况下,内源性阿片募集并接近Grp~+神经元,通过并行通路阻止痛的进一步产生。如果Grp~+神经元缺失,痛觉反应增加,而痒觉反应减少。这一新模型是脊髓非单一编码的一个很好范例,也能更好解释人类心理物理研究中的许多发现。
The coding of pain and itch information is a topic that scientists have focused and discussed for decades. However, the current coding theory (including: strength theory, specificity theory and selective theory) can not explain all the phenomena in the experiment. To elucidate the mechanism of pain and itching, researchers specifically labeled a class of interneurons (Grp) Grp ~ + neurons in the spinal cord. They studied these intermediate After neuronal function and characterization, a “Leaky Gate” model of pain and itch codes was proposed. The main content of this model is that there is a kind of Grp ~ + interneurons in the spinal cord segment. The neurons receive the synaptic afferent information of the pain and itch information directly from the primary sensory neurons. The effects of Grp ~ + neurons on pain and itch The sensory stimulus response shows different characteristics. Such neurons only transmit the signals of itching and weak pain. In the case of intense pain stimulation, the endogenous opioids recruits and approaches Grp ~ + neurons and prevents the further generation of pain through parallel pathways . If Grp ~ + neurons are missing, the pain response increases and the itch response decreases. This new model is a good example of non-unitary coding of the spinal cord and can better explain many of the findings in human psychophysical research.