Synaptic and cellular properties of the feedforward inhibitory circuit within the input layer of the cerebellar cortex.
Synaptic and cellular properties of the feedforward inhibitory circuit within the input layer of the cerebellar cortex.
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DOI：
10.1523/jneurosci.5469-07.2008
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发表时间：
2008-09-03
期刊：
影响因子：
--
通讯作者：
Silver RA
中科院分区：
文献类型：
--
作者：
Kanichay RT;Silver RA
准确地表示感觉刺激的时间对于小脑的核心功能--快速运动协调至关重要。前馈抑制与大脑几个区域的精确时间信号有关，但对小脑皮质输入层的这种类型的抑制电路知之甚少。我们研究了大鼠小脑片在近生理温度(35℃)下前馈抑制的突触特性。我们建立了以前未被描述的苔藓纤维-高尔基细胞-颗粒细胞通路可以作为一个功能前馈抑制电路。4个苔藓纤维的同步激活，将总共6个量子释放到一个高尔基细胞上，可以高时间精度地重置自发的高尔基细胞放电(200μS)。然而，在高频苔藓纤维刺激的过程中，高尔基细胞的放电率只有轻微的增加。高尔基体细胞活动与苔藓纤维放电速率的脱钩是由于每个动作电位后的强烈后超极化，阻止苔藓纤维高尔基体细胞信号传递约50ms。高尔基体细胞的前馈刺激在颗粒细胞中诱导了一种时间上精确的抑制电导，该电导抑制了苔藓纤维EPSC的兴奋作用。这种前馈电路的突触和细胞特性似乎可以在刺激开始时触发颗粒细胞的快速抑制电导，从而在多个苔藓纤维中产生强烈的活动爆发，从而保持颗粒细胞初始反应的时间精确度。
Precise representation of the timing of sensory stimuli is essential for rapid motor coordination, a core function of the cerebellum. Feed-forward inhibition has been implicated in precise temporal signalling in several regions of the brain, but little is known about this type of inhibitory circuit within the input layer of the cerebellar cortex. We have investigated the synaptic properties of feed-forward inhibition at near physiological temperatures (35°C) in rat cerebellar slices. We establish that the previously uncharacterized mossy fibre–Golgi cell–granule cell pathway can act as a functional feed-forward inhibitory circuit. The synchronous activation of 4 mossy fibres, releasing a total of 6 quanta onto a Golgi cell, can reset spontaneous Golgi cell firing with high temporal precision (200μs). However, only modest increases in Golgi cell firing rate were observed during trains of high frequency mossy fibre stimulation. This decoupling of Golgi cell activity from mossy fibre firing rate was due to a strong after-hyperpolarization following each action potential, preventing mossy fibre–Golgi cell signalling for ~50 ms. Feed-forward excitation of Golgi cells induced a temporally precise inhibitory conductance in granule cells that curtailed the excitatory action of the mossy fibre EPSC. The synaptic and cellular properties of this feed-forward circuit appear tuned to trigger a fast inhibitory conductance in granule cells at the onset of stimuli that produce intense bursts of activity in multiple mossy fibres, thereby conserving the temporal precision of the initial granule cell response.