Lopez-Garcia J A, King A E
Department of Physiology, University of Leeds, UK.
Eur J Neurosci. 1994 Jun 1;6(6):998-1007. doi: 10.1111/j.1460-9568.1994.tb00594.x.
Dorsal horn neurons in the young rat spinal cord-hindlimb preparation were physiologically classified as wide dynamic range (WDR), nociceptive specific (NS) or low threshold (LT) according to their excitatory responses to low and high intensity mechanical stimuli applied to the hindlimb skin. Two additional types were classified: neurons displaying only sub-threshold excitations (SUB) and neurons displaying inhibitory events (INH), such as inhibitory post-synaptic potentials or interruption of spontaneous spiking following cutaneous stimulation. Direct intracellular current injection revealed four different patterns of spiking behaviour: group A neurons were characterized by tonic firing in response to depolarizing current pulses; group B neurons were strongly phasic, producing only one spike at the beginning of the pulse; group A-B neurons generated an early unsustained (< 300 ms) burst of spikes; and group C neurons exhibited anomalous rectification in response to hyperpolarizing current which was followed by a voltage-dependent rebound excitation. A statistically significant (P < or = 0.01) association existed between a neuron's physiological classification and its electrophysiological profile. The majority of WDR neurons responded with tonic firing and were assigned to group A, while NS neurons were strongly represented in group A-B. All INH neurons were assigned to group C. LT neurons were distributed between groups A and A-B, and SUB neurons were distributed between groups A and B. These data indicate, firstly, that dorsal horn neurons possess heterogeneous membrane properties and, secondly, that a relationship exists between a neuron's biophysical profile and its excitatory or inhibitory response to peripheral cutaneous afferent stimulation. The implications for dorsal horn somatosensory processing are discussed.
根据对幼鼠脊髓 - 后肢标本中背角神经元对施加于后肢皮肤的低强度和高强度机械刺激的兴奋性反应，将其生理特性分为广动力范围（WDR）、伤害性特异（NS）或低阈值（LT）神经元。另外还划分出两种类型：仅表现为阈下兴奋的神经元（SUB）和表现出抑制性事件的神经元（INH），如抑制性突触后电位或皮肤刺激后自发放电的中断。直接细胞内电流注入揭示了四种不同的放电行为模式：A组神经元的特征是对去极化电流脉冲产生持续性放电；B组神经元强烈呈相位性，在脉冲开始时仅产生一个动作电位；A - B组神经元产生早期非持续性（<300毫秒）的动作电位爆发；C组神经元对超极化电流表现出反常整流，随后是电压依赖性反弹兴奋。神经元的生理分类与其电生理特征之间存在统计学显著（P≤0.01）关联。大多数WDR神经元以持续性放电做出反应，被归为A组，而NS神经元在A - B组中占比很大。所有INH神经元都归为C组。LT神经元分布在A组和A - B组之间，SUB神经元分布在A组和B组之间。这些数据表明，首先，背角神经元具有异质性膜特性；其次，神经元的生物物理特征与其对外周皮肤传入刺激的兴奋性或抑制性反应之间存在关联。文中还讨论了这些发现对背角体感处理的意义。
