Maturation of EPSCs and intrinsic membrane properties enhances precision at a cerebellar synapse
Maturation of EPSCs and intrinsic membrane properties enhances precision at a cerebellar synapse
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DOI：
10.1523/jneurosci.23-14-06074.2003
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发表时间：
2003-07-09
影响因子：
5.3
通讯作者：
Farrant, M
中科院分区：
文献类型：
--
作者：
Cathala, L;Brickley, S;Farrant, M
动作电位的时序是大脑信息编码的重要决定因素。EPSP的形状对脉冲产生的时间精度有重要影响。在这里，我们使用动态钳记录和被动神经元模型来研究突触电导波形和固有膜特性的发育变化如何影响小脑颗粒细胞的EPSP和动作电位的产生。我们记录了新形成的和成熟的苔藓纤维颗粒细胞突触上的EPSCs。量子电流和诱发电流均显示AMPA受体介导的成分显著加快。我们还发现了NMDA受体参与的年龄和活动依赖变化的证据。虽然AMPA和NMDA受体参与了未成熟突触的量子EPSCs，但需要多量子释放才能激活成熟突触的NMDA受体，这表明NMDA受体在发育中重新分布。这些突触电导波形的变化导致成熟颗粒细胞EPSP的快速上升和棘波潜伏期的缩短。成熟颗粒细胞的输入阻力也显著降低，有助于更快地衰退EPSP和减少尖峰抖动。我们认为，这些同步的发育变化，增加了EPSP-棘波耦合的时间精度，将增加小脑皮质输入层内处理感觉信息的保真度。
The timing of action potentials is an important determinant of information coding in the brain. The shape of the EPSP has a key influence on the temporal precision of spike generation. Here we use dynamic clamp recording and passive neuronal models to study how developmental changes in synaptic conductance waveform and intrinsic membrane properties combine to affect the EPSP and action potential generation in cerebellar granule cells. We recorded EPSCs at newly formed and mature mossy fiber - granule cell synapses. Both quantal and evoked currents showed a marked speeding of the AMPA receptor-mediated component. We also found evidence for age- and activity-dependent changes in the involvement of NMDA receptors. Although AMPA and NMDA receptors contributed to quantal EPSCs at immature synapses, multiquantal release was required to activate NMDA receptors at mature synapses, suggesting a developmental redistribution of NMDA receptors. These changes in the synaptic conductance waveform result in a faster rising EPSP and reduced spike latency in mature granule cells. Mature granule cells also have a significantly decreased input resistance, contributing to a faster decaying EPSP and a reduced spike jitter. We suggest that these concurrent developmental changes, which increase the temporal precision of EPSP-spike coupling, will increase the fidelity with which sensory information is processed within the input layer of the cerebellar cortex.