The dynamical response properties of neocortical neurons to temporally modulated noisy inputs in vitro
The dynamical response properties of neocortical neurons to temporally modulated noisy inputs in vitro
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DOI：
10.1093/cercor/bhm235
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发表时间：
2008-09-01
期刊：
影响因子：
3.7
通讯作者：
Giugliano, Michele
中科院分区：
文献类型：
--
作者：
Koendgen, Harold;Giesler, Caroline;Giugliano, Michele
皮层神经元通常根据电流-频率关系进行分类。这种静态描述不足以解释神经元对时变刺激的反应。理论研究表明，单细胞动态响应特性对于解释对快速输入瞬变的整体响应是必要的。此外，研究表明，输入噪声线性化并提高了响应带宽，并且噪声突触电流的密集和尖峰启动机制之间的相互作用决定了放电率的动态特性。为了测试这些模型预测，我们通过注入小幅度正弦波和背景噪声的叠加来估计第 5 层锥体细胞的线性响应特性。我们描述了许多刺激试验和一系列振荡频率 (1-1000 Hz) 的诱发放电概率，在改变噪声统计数据的同时量化响应幅度和相移。我们发现神经元跟踪出乎意料的快速瞬变，因为它们的响应幅度在高达 200 Hz 的范围内没有衰减。该截止频率高于被动膜特性（类似于 50 Hz）和平均发射速率（类似于 20 Hz）设定的限制，并且不受输入变化率的影响。最后，在 200 Hz 以上，响应幅度按照幂律衰减，其指数与背景噪声引起的电压波动无关。
Cortical neurons are often classified by current-frequency relationship. Such a static description is inadequate to interpret neuronal responses to time-varying stimuli. Theoretical studies suggested that single-cell dynamical response properties are necessary to interpret ensemble responses to fast input transients. Further, it was shown that input-noise linearizes and boosts the response bandwidth, and that the interplay between the barrage of noisy synaptic currents and the spike-initiation mechanisms determine the dynamical properties of the firing rate. To test these model predictions, we estimated the linear response properties of layer 5 pyramidal cells by injecting a superposition of a small-amplitude sinusoidal wave and a background noise. We characterized the evoked firing probability across many stimulation trials and a range of oscillation frequencies (1-1000 Hz), quantifying response amplitude and phase-shift while changing noise statistics. We found that neurons track unexpectedly fast transients, as their response amplitude has no attenuation up to 200 Hz. This cut-off frequency is higher than the limits set by passive membrane properties (similar to 50 Hz) and average firing rate (similar to 20 Hz) and is not affected by the rate of change of the input. Finally, above 200 Hz, the response amplitude decays as a power-law with an exponent that is independent of voltage fluctuations induced by the background noise.