Subthreshold voltage noise of rat neocortical pyramidal neurones
Subthreshold voltage noise of rat neocortical pyramidal neurones
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DOI：
10.1113/jphysiol.2004.080903
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发表时间：
2005-04-01
影响因子：
5.5
通讯作者：
Yarom, Y
中科院分区：
文献类型：
--
作者：
Jacobson, GA;Diba, K;Yarom, Y
神经元是噪声元素。噪声来自内在和外在来源，并表现为膜电位的波动。这些波动限制了神经元输出的准确性，但也被认为扮演了计算的角色。本文详细研究了大鼠大脑新皮层脑片上IV-V层锥体神经元索马胞体的电压噪声幅度和频谱。系统地分析了噪声与保持电位、突触活动和Na+电导的关系。我们证明，电压噪声增加非线性的细胞去极化（从标准偏差（S.D.）在-75 mV时为0.19 mV至S.D.在-55 mV时为0.54 mV）。由于Na+电导的电压依赖性，电压噪声的增加伴随着电池阻抗的增加。阻抗增加占电压噪声增加的大部分（70%）。电压噪声和阻抗的增加仅限于低频范围（0.2-2 Hz）。在高频范围（5-100 Hz），电压噪声由突触活动支配。在我们的切片制备中，突触噪声对细胞阻抗的影响很小。一个最小的模型再现定性这些数据。我们的研究结果表明，离子通道噪声有助于显着的膜电压波动在阈下电压范围内，Na+电导起着关键作用，在确定这种噪声的幅度作为一个电压依赖性放大器的低频瞬态。
Neurones are noisy elements. Noise arises from both intrinsic and extrinsic sources, and manifests itself as fluctuations in the membrane potential. These fluctuations limit the accuracy of a neurone's output but have also been suggested to play a computational role. We present a detailed study of the amplitude and spectrum of voltage noise recorded at the soma of layer IV-V pyramidal neurones in slices taken from rat neocortex. The dependence of the noise on holding potential, synaptic activity and Na+ conductance is systematically analysed. We demonstrate that voltage noise increases non-linearly as the cell depolarizes (from a standard deviation (S.D.) of 0.19 mV at -75 mV to an S.D. of 0.54 mV at -55 mV). The increase in voltage noise is accompanied by an increase in the cell impedance, due to voltage dependence of Na+ conductance. The impedance increase accounts for the majority (70%) of the voltage noise increase. The increase in voltage noise and impedance is restricted to the low-frequency range (0.2-2 Hz). At the high frequency range (5-100 Hz) the voltage noise is dominated by synaptic activity. In our slice preparation, synaptic noise has little effect on the cell impedance. A minimal model reproduces qualitatively these data. Our results imply that ion channel noise contributes significantly to membrane voltage fluctuations at the subthreshold voltage range, and that Na+ conductance plays a key role in determining the amplitude of this noise by acting as a voltage-dependent amplifier of low-frequency transients.