Cortical action potential backpropagation explains spike threshold variability and rapid-onset kinetics.
Cortical action potential backpropagation explains spike threshold variability and rapid-onset kinetics.
复制标题
DOI：
10.1523/jneurosci.1613-08.2008
复制
发表时间：
2008-07-16
期刊：
影响因子：
--
通讯作者：
McCormick DA
中科院分区：
文献类型：
--
作者：
Yu Y;Shu Y;McCormick DA
体内新皮质动作电位反应的特征是相当大的阈值变异性，因此即使在看似相同的条件下，时间和速率也存在变异性。这一发现表明，准确的感觉运动整合和处理需要皮质群。在细胞内，试验间的变异性不仅源于突触活动的变化，而且还源于突触活动向动作电位模式的转化。通过同步轴突和体细胞记录以及计算模拟，我们证明了轴突初始段中动作电位的启动，随后这些尖峰在整个神经元中的反向传播导致突触和动作电位事件之间关系的扭曲。此外，这种反向传播还会导致动作电位底部膜电位的异常高的上升率。由尖峰反向传播引起的突触输入的幅度时间过程和动作电位输出之间关系的扭曲导致在体细胞水平上出现高尖峰阈值变异性。在尖峰起始点，即轴突初始段，阈值变异性相当小。我们的结果表明，皮层神经元中尖峰的产生很大程度上符合霍奇金-赫胥黎理论的预期，并且比之前认为的更精确。
Neocortical action potential responses in vivo are characterized by considerable threshold variability, and thus timing and rate variability, even under seemingly identical conditions. This finding suggests that cortical ensembles are required for accurate sensorimotor integration and processing. Intracellularly, trial-to-trial variability results not only from variation in synaptic activities, but also in the transformation of these into patterns of action potentials. Through simultaneous axonal and somatic recordings and computational simulations, we demonstrate that the initiation of action potentials in the axon initial segment followed by backpropagation of these spikes throughout the neuron results in a distortion of the relationship between the timing of synaptic and action potential events. In addition, this backpropagation also results in an unusually high rate of rise of membrane potential at the foot of the action potential. The distortion of the relationship between the amplitude time course of synaptic inputs and action potential output caused by spike back-propagation results in the appearance of high spike threshold variability at the level of the soma. At the point of spike initiation, the axon initial segment, threshold variability is considerably less. Our results indicate that spike generation in cortical neurons is largely as expected by Hodgkin—Huxley theory and is more precise than previously thought.