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首页> 外文期刊>Journal of Neurophysiology >Differences in inhibitory synaptic input between layer II-III and layer V neurons of the cat neocortex.
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Differences in inhibitory synaptic input between layer II-III and layer V neurons of the cat neocortex.

机译：猫新皮层的II-III层和V层神经元之间抑制突触输入的差异。

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摘要

1. The goal of this study was to compare the relative effectiveness of intrinsic inhibitory synaptic inputs in different layers of the cat motor cortex. Postsynaptic potentials (PSPs) were evoked in neurons located in the superficial (layer II-III) or deep layers (layer V) by local extracellular stimulation in vitro. Electrophysiological properties and intracellular filling indicated that the recorded neurons were pyramidal cells. 2. The shape and time course of the evoked PSPs differed. Layer II-III cells showed stereotyped triphasic PSPs consisting of a fast excitatory PSP (fEPSP) and a fast and slow inhibitory PSP (fIPSP and sIPSP, respectively). PSPs in layer V cells, in contrast, were much more variable, mainly depolarizing at resting membrane potential, and lacked a hyperpolarizing IPSP in 84% of neurons tested at rest. 3. Blockade of glutaminergic neurotransmission with 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) and D-2-amino-5-phosphonovaleric acid (AP5) revealed that fIPSPs could be evoked inall layer V cells by local stimulation of the superficial or deep layers, even in those that showed small or no IPSPs in control perfusate. Small (< 1 mV) isolated sIPSPs were evoked in only one-fifth of layer V cells when the deep layers were stimulated, and in about one-half of the layer V cells when the superficial layers were stimulated. In layer II-III cells, stimulation of the superficial layers always resulted in fIPSP-sIPSP combinations. No IPSPs could be evoked in layer II-III neurons by stimulating the deep layers after glutaminergic blockade. Selective blockade of gamma-aminobutyric acid-A (GABAA) or GABAB receptor-mediated neurotransmission showed that in both cell types fIPSPs were due to GABAA receptor stimulation, whereas sIPSPs were mediated by GABAB receptors. 4. Isolated fIPSPs were recorded in perfusate containing CNQX, AP5, and the GABAB antagonist CGP 35348. The rise and decay times of the fIPSPs in layer II-III cells were significantly longer than those in layer V cells. Rise and decay times normalized for differences in membrane time constant were not significantly different, however, suggesting that the intrinsic membrane properties of the postsynaptic membrane account for the difference in time course of the fIPSPs in these two cell types. 5. Selective blockade of the inward rectifier current Ih with extracellular Cs+ showed that this conductance functions to shorten and attenuate fIPSPs in layer V cells. In contrast, Ih is absent or small in layer II-III cells, and, consequently, Cs+ had little or no effect on the fIPSPs evoked in these cells.(ABSTRACT TRUNCATED AT 400 WORDS)
机译：1.这项研究的目的是比较猫运动皮层不同层中固有抑制性突触输入的相对有效性。突触后电位（PSPs）在体外通过局部细胞外刺激在位于浅层（II-III层）或深层（V层）的神经元中引起。电生理特性和细胞内填充表明所记录的神经元是锥体细胞。 2.诱发的PSP的形状和时程不同。 II-III层细胞显示出定型的三相PSP，由快速兴奋性PSP（fEPSP）和快速抑制性PSP和缓慢抑制性PSP（分别为fIPSP和sIPSP）组成。相比之下，V层细胞中的PSP更具可变性，主要在静息膜电位消极化，并且在静息测试的84％神经元中缺乏超极化IPSP。 3.用6-氰基-7-硝基喹喔啉-2,3-二酮（CNQX）和D-2-氨基-5-膦酰戊酸（AP5）阻断谷氨酰胺能神经传递表明，fIPSPs可以通过局部刺激在整个V层细胞中诱发表层或深层，即使在对照灌流液中显示出很小或没有IPSP的那些层。当刺激深层时，仅在五分之一的V层细胞中引起小的（<1 mV）分离的sIPSP，而当刺激表层时，仅引起一半的V型细胞。在II-III层细胞中，表层的刺激总是导致fIPSP-sIPSP组合。在谷氨酰胺能阻滞后，通过刺激深层，在II-III层神经元中不会诱发IPSP。对γ-氨基丁酸-A（GABAA）或GABAB受体介导的神经传递的选择性阻滞表明，在两种细胞类型中，fIPSPs都是由于GABAA受体刺激引起的，而sIPSPs是由GABAB受体介导的。 4.在包含CNQX，AP5和GABAB拮抗剂CGP 35348的灌注液中记录分离的fIPSPs。II-III层细胞中fIPSPs的上升和衰减时间明显长于V层细胞。标准化的膜时间常数差异的上升和下降时间没有显着差异，但是，这表明突触后膜的固有膜特性解释了这两种细胞类型中fIPSPs的时程差异。 5.用胞外Cs +选择性阻断内向整流器电流Ih，表明该电导的作用是缩短和减弱V层细胞中的fIPSPs。相比之下，II-III层细胞中缺少Ih或很小，因此Cs +对这些细胞中诱发的fIPSP几乎没有或没有影响。（摘要截短了400字）

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