Department of Bioengineering, Brain Institute, University of Utah, Salt Lake City, Utah 84112, USA.
J Neurosci. 2011 Mar 9;31(10):3880-93. doi: 10.1523/JNEUROSCI.5076-10.2011.
Modulating the gain of the input-output function of neurons is critical for processing of stimuli and network dynamics. Previous gain control mechanisms have suggested that voltage fluctuations play a key role in determining neuronal gain in vivo. Here we show that, under increased membrane conductance, voltage fluctuations restore Na(+) current and reduce spike frequency adaptation in rat hippocampal CA1 pyramidal neurons in vitro. As a consequence, membrane voltage fluctuations produce a leftward shift in the frequency-current relationship without a change in gain, relative to an increase in conductance alone. Furthermore, we show that these changes have important implications for the integration of inhibitory inputs. Due to the ability to restore Na(+) current, hyperpolarizing membrane voltage fluctuations mediated by GABA(A)-like inputs can increase firing rate in a high-conductance state. Finally, our data show that the effects on gain and synaptic integration are mediated by voltage fluctuations within a physiologically relevant range of frequencies (10-40 Hz).
调节神经元的输入-输出函数的增益对于刺激处理和网络动力学至关重要。先前的增益控制机制表明，电压波动在体内决定神经元增益方面起着关键作用。在这里，我们表明，在膜电导增加的情况下，电压波动在体外恢复大鼠海马 CA1 锥体神经元中的钠电流并减少尖峰频率适应。因此，与仅增加电导相比，膜电压波动在不改变增益的情况下导致频率-电流关系向左移动。此外，我们表明这些变化对抑制性输入的整合具有重要意义。由于能够恢复钠电流，由 GABA(A)样输入介导的超极化膜电压波动可以在高电导状态下增加放电率。最后，我们的数据表明，增益和突触整合的影响是由生理相关频率范围内（10-40 Hz）的电压波动介导的。
