Stevens C F, Zador A M
Howard Hughes Medical Institute, Salk Institute for Biological Studies, La Jolla, California 92037, USA.
Nat Neurosci. 1998 Jul;1(3):210-7. doi: 10.1038/659.
Cortical neurons in the waking brain fire highly irregular, seemingly random, spike trains in response to constant sensory stimulation, whereas in vitro they fire regularly in response to constant current injection. To test whether, as has been suggested, this high in vivo variability could be due to the postsynaptic currents generated by independent synaptic inputs, we injected synthetic synaptic current into neocortical neurons in brain slices. We report that independent inputs cannot account for this high variability, but this variability can be explained by a simple alternative model of the synaptic drive in which inputs arrive synchronously. Our results suggest that synchrony may be important in the neural code by providing a means for encoding signals with high temporal fidelity over a population of neurons.
清醒大脑中的皮层神经元在受到持续感觉刺激时会产生高度不规则、看似随机的动作电位序列，而在体外，它们在受到持续电流注入时会规律地放电。为了测试，正如有人所提出的，这种在体内的高变异性是否可能是由独立突触输入产生的突触后电流所致，我们将合成突触电流注入脑片的新皮层神经元中。我们报告称，独立输入无法解释这种高变异性，但这种变异性可以通过一个简单的突触驱动替代模型来解释，在该模型中输入是同步到达的。我们的结果表明，同步性可能在神经编码中很重要，因为它为在一群神经元上以高时间保真度编码信号提供了一种方式。
