Richardson T L, Turner R W, Miller J J
Brain Res. 1984 Mar 5;294(2):255-62. doi: 10.1016/0006-8993(84)91037-0.
The influence of extracellular fields on the transmembrane potential (TMP) of CA1 pyramidal neurons was investigated following both ortho- and antidromic stimulation in the in vitro hippocampal slice preparation. A short latency negative deflection on the intracellular potential coincided with the falling phase of the extracellular population spike. Subtraction of extracellular field potentials from ground referenced intracellular records revealed a sharp depolarizing wave of the TMP superimposed upon the underlying synaptic potential. This graded depolarization was capable of discharging CA1 cells and displayed a parallel shift in latency and amplitude with the extracellular population spike. A similar depolarizing wave was associated with the antidromically evoked population spike which persisted following blockade of synaptic activity. Finally, multiple population spike activity similar to that observed during epileptiform discharge was associated with repetitive depolarizing waves of the TMP. These data suggest that extracellular field potentials can ephaptically discharge CA1 neurons and may play a role in recruitment and synchronization of neuronal activity in the hippocampus.
在体外海马脑片制备中，通过正向和逆向刺激研究了细胞外电场对CA1锥体神经元跨膜电位（TMP）的影响。细胞内电位上的一个短潜伏期负向偏转与细胞外群体峰电位的下降期同时出现。从接地参考的细胞内记录中减去细胞外场电位，揭示了叠加在基础突触电位上的TMP的一个尖锐去极化波。这种分级去极化能够使CA1细胞放电，并与细胞外群体峰电位在潜伏期和幅度上呈现平行变化。类似的去极化波与逆向诱发的群体峰电位相关，在突触活动被阻断后该峰电位仍然存在。最后，类似于在癫痫样放电期间观察到的多个群体峰电位活动与TMP的重复性去极化波相关。这些数据表明，细胞外场电位可以通过电紧张作用使CA1神经元放电，并可能在海马体神经元活动的募集和同步中发挥作用。
