Properties of a population of GABAergic cells in murine auditory cortex weakly excited by thalamic stimulation.
Properties of a population of GABAergic cells in murine auditory cortex weakly excited by thalamic stimulation.
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丘脑刺激微弱兴奋的小鼠听觉皮层中 GABA 能细胞群的特性。
DOI：
10.1152/jn.00484.2006
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发表时间：
2006
影响因子：
2.5
通讯作者：
Banks,MatthewI
中科院分区：
文献类型：
--
作者：
Verbny,YakovI;Erdelyi,Ferenc;Szabo,Gabor;Banks,MatthewI
由丘脑皮层（TC）传入触发的前馈抑制可使听皮层（ACx）锥体细胞的起始反应更加尖锐，并形成感受野。以前的研究只集中在位于初级ACx，从腹内侧膝状体的密集丘脑投射的目标IV层及其周围的中间神经元。我们研究了位于整个I-V层的前馈中间神经元的群体，并通过初级和非初级丘脑的传入神经激活，使用从表达绿色荧光蛋白的小鼠大脑皮层GABA能细胞亚群中的谷氨酸脱羧酶（GAD 65）启动子控制下获得的听觉TC脑切片的记录。我们研究了这些interneurons和锥体细胞在ACx丘脑刺激和超和去极化电流脉冲的反应。大多数中间神经元对丘脑刺激表现出单突触反应，但这种兴奋是弱的和阈下的。中间神经元具有多极树突形态，广泛而密集的轴突突起从索马延伸数百微米。在II-IV层锥体细胞中，丘脑兴奋性突触后电位显着大于中间神经元，并且在40%的细胞中为超阈值，但在这些细胞中，没有前馈抑制的证据。与此相反，前馈抑制中观察到的12个18层V锥体细胞。因此，前馈抑制ACx颗粒上层是弱的，这些interneurons需要一致的兴奋被激活丘脑输入。
Feedforward inhibition triggered by thalamocortical (TC) afferents sharpens onset responses and shapes receptive fields of pyramidal cells in auditory cortex (ACx). Previous studies focused only on interneurons located in and around layer IV in primary ACx, target of the dense thalamic projections from ventral medial geniculate. We investigated a population of feedforward interneurons located throughout layers I–V and activated by both afferents from primary and nonprimary thalamus using recordings from auditory TC brain slices obtained from mice expressing green fluorescent protein under control of the glutamic acid decarboxylase (GAD65) promoter in a subpopulation of cortical GABAergic cells. We studied the responses of these interneurons and of pyramidal cells in ACx to thalamic stimulation and to hyper- and depolarizing current pulses. Most interneurons exhibited monosynaptic responses to thalamic stimulation, but this excitation was weak and subthreshold. Interneurons had multipolar dendritic morphology with widespread and dense axonal projections extending several hundred micrometers from the soma. In pyramidal cells from layers II–IV, thalamic excitatory postsynaptic potentials were significantly larger than in interneurons and were superthreshold in 40% of cells, but in these cells, there was no evidence of feedforward inhibition. By contrast, feedforward inhibition was observed in 12 of 18 layer V pyramidal cells. Thus feedforward inhibition in supragranular layers of ACx is weak, and these interneurons require coincident excitation to be activated by thalamic inputs.