Computation and Neural Systems, California Institute of Technology, Pasadena, CA 91125, USA.
J Neurophysiol. 2009 Dec;102(6):3340-51. doi: 10.1152/jn.91365.2008. Epub 2009 Sep 30.
We simulated the shape and amplitude of extracellular action potentials (APs or "spikes") using biophysical models based on detailed reconstructions of single neurons from the cat's visual cortex. We compared these predictions with spikes recorded from the cat's primary visual cortex under a standard protocol. The experimental data were derived from a large number of neurons throughout all layers. The majority of spikes were biphasic, with a dominant negative peak (mean amplitude, -0.11 mV), whereas a minority of APs had a dominant positive peak of +0.54-mV mean amplitude, with a maximum of +1.5 mV. The largest positive amplitude spikes were recorded in layer 5. The simulations demonstrated that a pyramidal neuron under known biophysical conditions may generate a negative peak with amplitude up to -1.5 mV, but that the amplitude of the positive peak may be at most 0.5 mV. We confirmed that spikes with large positive peaks were not produced by juxtacellular patch recordings. We conclude that there is a significant gap in our present understanding of either the spike-generation process in pyramidal neurons, the biophysics of extracellular recording, or both.
我们使用基于猫视觉皮层单个神经元详细重建的生物物理模型来模拟细胞外动作电位（AP 或“尖峰”）的形状和幅度。我们将这些预测与在标准方案下从猫的初级视觉皮层记录的尖峰进行了比较。实验数据来自所有层中的大量神经元。大多数尖峰是双相的，具有主导的负峰（平均幅度为-0.11 mV），而少数尖峰具有主导的正峰，平均幅度为+0.54 mV，最大幅度为+1.5 mV。最大的正尖峰幅度记录在第 5 层。模拟表明，在已知的生物物理条件下，一个锥体细胞可能会产生幅度高达-1.5 mV 的负峰，但正峰的幅度可能最大为 0.5 mV。我们证实，具有大正峰的尖峰不是由细胞外贴附记录产生的。我们的结论是，我们目前对锥体细胞的尖峰产生过程、细胞外记录的生物物理学或两者都有很大的理解差距。
