Dynamics of the firing probability of noisy integrate-and-fire neurons
Dynamics of the firing probability of noisy integrate-and-fire neurons
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DOI：
10.1162/089976602320264015
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发表时间：
2002-09-01
影响因子：
2.9
通讯作者：
Brunel, N
中科院分区：
文献类型：
--
作者：
Fourcaud, N;Brunel, N
由于突触活动，活体中的皮质神经元经历了持续的轰击，突触活动是噪声的主要来源。在这里，我们研究了具有不同真实感水平的突触过滤噪声对整合和激发神经元动力学的影响。噪声输入由白色(对于瞬时突触)或有色(对于具有有限松弛时间的突触)噪声建模。通过对问题的小参数展开Fokker-Planck方程，得到了响应于振荡输入电流的放电概率调制的解析结果--当调制的幅度与背景放电速率相比较小，且突触时间常数与膜时间常数相比较小时。我们报告的详细计算表明，如果在突触电流模型中包括突触衰减时间常数，则由于振荡输入引起的神经元的放电速率调制在高频范围内保持有限，没有相位滞后。此外，我们还刻画了中间衰变时间的低频行为和高频极限行为。我们还表征了在突触电流中引入上升时间的影响，以及几种不同动力学的突触受体的存在。在这两种情况下，我们使用数值模拟来确定完全描述神经元反应的有效衰减时间常数。
Cortical neurons in vivo undergo a continuous bombardment due to synaptic activity, which acts as a major source of noise. Here, we investigate the effects of the noise filtering by synapses with various levels of realism on integrate-and-fire neuron dynamics. The noise input is modeled by white (for instantaneous synapses) or colored (for synapses with a finite relaxation time) noise. Analytical results for the modulation of firing probability in response to an oscillatory input current are obtained by expanding a Fokker-Planck equation for small parameters of the problem-when both the amplitude of the modulation is small compared to the background firing rate and the synaptic time constant is small compared to the membrane time constant. We report here the detailed calculations showing that if a synaptic decay time constant is included in the synaptic current model, the firing-rate modulation of the neuron due to an oscillatory input remains finite in the high-frequency limit with no phase lag. In addition, we characterize the low-frequency behavior and the behavior of the high-frequency limit for intermediate decay times. We also characterize the effects of introducing a rise time to the synaptic currents and the presence of several synaptic receptors with different kinetics. In both cases, we determine, using numerical simulations, an effective decay time constant that describes the neuronal response completely.