Akeyson E W, Schramm L P
Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
Am J Physiol. 1994 Jan;266(1 Pt 2):R257-67. doi: 10.1152/ajpregu.1994.266.1.R257.
To better understand the spinal transmission of visceral afferent information, we conducted neurophysiological studies of single spinal neurons that receive input from the greater splanchnic nerve (GSN). Extracellular single-neuron recordings were made in the thoracic spinal cord of chloralose-anesthetized, paralyzed, and artificially ventilated rats, some of which had undergone acute spinal transection at C1. Neurons were divided into four classes according to their responses to GSN stimulation: one-burst excitatory, two-burst excitatory, biphasic, and inhibited. We then studied the characteristics of the convergent somatic input to each class of neurons using either natural somatic stimuli or electrical stimulation of the iliohypogastric nerve (IHN). Most splanchnic input was mediated by unmyelinated fibers, whereas somatic input was mediated by both unmyelinated and small myelinated fibers. Most of the neurons exhibited somatic receptive fields, and the majority responded to both innocuous and noxious somatic stimuli. However, a small number could be excited only by GSN stimulation. Although a careful analysis of response characteristics indicated that there was a tendency for neurons to exhibit similar responses to electrical stimulation of the GSN and the IHN, we observed many combinations of somatic and visceral responses. We suggest that visceral afferent activity, in addition to being processed via convergent somatovisceral pathways, may be processed by neurons that convey only visceral information or by neurons in which visceral and somatic information is differentially coded.
为了更好地理解内脏传入信息的脊髓传递，我们对接受来自内脏大神经（GSN）输入的单个脊髓神经元进行了神经生理学研究。在水合氯醛麻醉、麻痹并人工通气的大鼠胸段脊髓中进行细胞外单神经元记录，其中一些大鼠在C1水平进行了急性脊髓横断。根据神经元对GSN刺激的反应将其分为四类：单峰兴奋性、双峰兴奋性、双相性和抑制性。然后，我们使用自然躯体刺激或髂腹下神经（IHN）电刺激研究了每类神经元的汇聚性躯体输入特征。大多数内脏传入输入由无髓纤维介导，而躯体输入由无髓和小的有髓纤维介导。大多数神经元表现出躯体感受野，并且大多数对无害和有害的躯体刺激都有反应。然而，少数神经元仅能被GSN刺激兴奋。尽管对反应特征的仔细分析表明，神经元对GSN和IHN电刺激表现出相似反应存在一定趋势，但我们观察到了许多躯体和内脏反应的组合。我们认为，内脏传入活动除了通过汇聚性体-内脏通路进行处理外，可能还由仅传递内脏信息的神经元或对内脏和躯体信息进行差异编码的神经元进行处理。
