de Polavieja Gonzalo G, Harsch Annette, Kleppe Ingo, Robinson Hugh P C, Juusola Mikko
Physiological Laboratory, University of Cambridge, Cambridge CB2 3EG, United Kingdom.
J Neurosci. 2005 Jun 8;25(23):5657-65. doi: 10.1523/JNEUROSCI.0242-05.2005.
Action potentials have been shown to shunt synaptic charge to a degree that depends on their waveform. In this way, they participate in synaptic integration, and thus in the probability of generating succeeding action potentials, in a shape-dependent way. Here we test whether the different action potential waveforms produced during dynamical stimulation in a single cortical neuron carry information about the conductance stimulus history. When pyramidal neurons in rat visual cortex were driven by a conductance stimulus that resembles natural synaptic input, somatic action potential waveforms showed a large variability that reliably signaled the history of the input for up to 50 ms before the spike. The correlation between stimulus history and action potential waveforms had low noise, resulting in information rates that were three to four times larger than for the instantaneous spike rate. The reliable correlation between stimulus history and spike waveforms then acts as a local encoding at the single-cell level. It also directly affects neuronal communication as different waveforms influence the production of succeeding spikes via differential shunting of synaptic charge. Modeling was used to show that slow conductances can implement memory of the stimulus history in cortical neurons, encoding this information in the spike shape.
动作电位已被证明会以一种取决于其波形的程度分流突触电荷。通过这种方式，它们以形状依赖的方式参与突触整合，进而影响产生后续动作电位的概率。在这里，我们测试在单个皮层神经元的动态刺激过程中产生的不同动作电位波形是否携带有关电导刺激历史的信息。当大鼠视觉皮层中的锥体神经元由类似于自然突触输入的电导刺激驱动时，体细胞动作电位波形表现出很大的变异性，这种变异性能可靠地反映出在动作电位发放前长达50毫秒的输入历史。刺激历史与动作电位波形之间的相关性噪声较低，导致信息率比瞬时发放率大三到四倍。刺激历史与动作电位波形之间可靠的相关性随后在单细胞水平上起到局部编码的作用。它还直接影响神经元通信，因为不同的波形通过突触电荷的差异分流影响后续动作电位的产生。建模结果表明，缓慢的电导可以在皮层神经元中实现对刺激历史的记忆，并将这些信息编码在动作电位的形状中。
