Integration of quanta in cerebellar granule cells during sensory processing
Integration of quanta in cerebellar granule cells during sensory processing
复制标题
DOI：
10.1038/nature02442
复制
发表时间：
2004-04-22
期刊：
影响因子：
64.8
通讯作者：
Häusser, M
中科院分区：
文献类型：
--
作者：
Chadderton, P;Margrie, TW;Häusser, M
为了理解皮层结构输入层执行的计算，确定感觉诱发的突触输入与输出尖峰的结果模式之间的关系至关重要。在小脑中，颗粒细胞构成输入层，将苔藓纤维信号转化为平行纤维输入浦肯野细胞(1)。到目前为止，它们的小尺寸和致密的包装（1,2）阻碍了个体颗粒细胞在体内的记录。在这里，我们使用全细胞膜片钳记录来显示由体感刺激引起的苔藓纤维突触电流与由此产生的颗粒细胞输出模式之间的关系。颗粒细胞表现出较低的持续放电率，部分原因是由于GABA(a) （γ -氨基丁酸a型）受体介导的强直性抑制性传导抑制了兴奋性。感觉刺激产生了苔藓纤维兴奋性突触后电流（EPSCs）的爆发，这些电流叠加在一起引发了刺突的爆发。值得注意的是，只有少数量子epsc才能诱发这些尖峰爆发，而自发的苔藓纤维输入只有在抑制减少时才会触发尖峰。我们的研究结果表明，小脑的输入层以高信噪比平衡了灵敏的灵敏度。颗粒细胞爆发最适合触发平行纤维突触的谷氨酸受体激活（3-5）和可塑性（6-8），在小脑中提供输入表征和记忆存储之间的联系。
To understand the computations performed by the input layers of cortical structures, it is essential to determine the relationship between sensory-evoked synaptic input and the resulting pattern of output spikes. In the cerebellum, granule cells constitute the input layer, translating mossy fibre signals into parallel fibre input to Purkinje cells(1). Until now, their small size and dense packing(1,2) have precluded recordings from individual granule cells in vivo. Here we use whole-cell patch-clamp recordings to show the relationship between mossy fibre synaptic currents evoked by somatosensory stimulation and the resulting granule cell output patterns. Granule cells exhibited a low ongoing firing rate, due in part to dampening of excitability by a tonic inhibitory conductance mediated by GABA(A) (gamma-aminobutyric acid type A) receptors. Sensory stimulation produced bursts of mossy fibre excitatory postsynaptic currents (EPSCs) that summate to trigger bursts of spikes. Notably, these spike bursts were evoked by only a few quantal EPSCs, and yet spontaneous mossy fibre inputs triggered spikes only when inhibition was reduced. Our results reveal that the input layer of the cerebellum balances exquisite sensitivity with a high signal-to-noise ratio. Granule cell bursts are optimally suited to trigger glutamate receptor activation(3-5) and plasticity(6-8) at parallel fibre synapses, providing a link between input representation and memory storage in the cerebellum.