Qu Guojie, Fan Boqiang, Fu Xin, Yu Yuguo
State Key Laboratory of Medical Neurobiology, School of Life Science, Human Phenome Institute, Institute of Brain Science, Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai, China.
Front Cell Neurosci. 2019 Jul 11;13:311. doi: 10.3389/fncel.2019.00311. eCollection 2019.
What type of principle features intrinsic inside of the fluctuated input signals could drive neurons with the maximal excitations is one of the crucial neural coding issues. In this article, we examined both experimentally and theoretically the cortical neuronal responsivity (including firing rate and spike timing reliability) to input signals with different intrinsic correlational statistics (e.g., white-type noise, showed 1/f power spectrum, pink noise 1/f, and brown noises 1/f) and different frequency ranges. Our results revealed that the response sensitivity and reliability of cortical neurons is much higher in response to 1/f noise stimuli with long-term correlations than 1/f with short-term correlations for a broad frequency range, and also higher than 1/f for all frequency ranges. In addition, we found that neuronal sensitivity diverges to opposite directions for 1/f noise comparing with 1/f white noise as a function of cutoff frequency of input signal. As the cutoff frequency is progressively increased from 50 to 1,000 Hz, the neuronal responsiveness increased gradually for 1/f noise, while decreased exponentially for white noise. Computational simulations of a general cortical model revealed that, neuronal sensitivity and reliability to input signal statistics was majorly dominated by fast sodium inactivation, potassium activation, and membrane time constants.
在波动的输入信号中，何种类型的内在特征能够驱动神经元产生最大兴奋，这是神经编码的关键问题之一。在本文中，我们通过实验和理论研究了皮质神经元对具有不同内在相关统计特性（例如，白噪声型、呈现1/f功率谱的粉红噪声、1/f的棕色噪声）以及不同频率范围的输入信号的反应性（包括放电率和放电时间可靠性）。我们的结果表明，在较宽频率范围内，皮质神经元对具有长期相关性的1/f噪声刺激的反应敏感性和可靠性远高于具有短期相关性的1/f噪声，并且在所有频率范围内也高于白噪声。此外，我们发现，作为输入信号截止频率的函数，与白噪声相比，1/f噪声的神经元敏感性在相反方向上存在差异。随着截止频率从50Hz逐渐增加到1000Hz，1/f噪声的神经元反应性逐渐增加，而白噪声的神经元反应性则呈指数下降。一个通用皮质模型的计算模拟表明，神经元对输入信号统计特性的敏感性和可靠性主要由快速钠失活、钾激活和膜时间常数决定。
