Institute of Neuroscience and Psychology, University of Glasgow, , Glasgow G12 8QB, UK.
Philos Trans R Soc Lond B Biol Sci. 2014 Jan 20;369(1637):20120467. doi: 10.1098/rstb.2012.0467. Print 2014 Mar 5.
The precise timing of action potentials of sensory neurons relative to the time of stimulus presentation carries substantial sensory information that is lost or degraded when these responses are summed over longer time windows. However, it is unclear whether and how downstream networks can access information in precise time-varying neural responses. Here, we review approaches to test the hypothesis that the activity of neural populations provides the temporal reference frames needed to decode temporal spike patterns. These approaches are based on comparing the single-trial stimulus discriminability obtained from neural codes defined with respect to network-intrinsic reference frames to the discriminability obtained from codes defined relative to the experimenter's computer clock. Application of this formalism to auditory, visual and somatosensory data shows that information carried by millisecond-scale spike times can be decoded robustly even with little or no independent external knowledge of stimulus time. In cortex, key components of such intrinsic temporal reference frames include dedicated neural populations that signal stimulus onset with reliable and precise latencies, and low-frequency oscillations that can serve as reference for partitioning extended neuronal responses into informative spike patterns.
感觉神经元动作电位的精确时间相对于刺激呈现的时间携带了大量的感觉信息，当这些反应在更长的时间窗口内被累加时，这些信息就会丢失或降级。然而，目前尚不清楚下游网络是否以及如何访问精确的时变神经反应中的信息。在这里，我们回顾了一些方法来检验这样的假设，即神经网络的活动提供了解码时变尖峰模式所需的时间参考框架。这些方法基于将相对于网络内在参考框架定义的神经码获得的单试刺激可辨别性与相对于实验者计算机时钟定义的码获得的可辨别性进行比较。这一形式主义在听觉、视觉和体感数据中的应用表明，即使只有很少或没有关于刺激时间的独立外部知识，毫秒级的尖峰时间所携带的信息也可以被可靠地解码。在大脑皮层中，这种内在时间参考框架的关键组成部分包括专门的神经群体，它们以可靠和精确的潜伏期来标记刺激的开始，以及低频振荡，它们可以作为将扩展的神经元反应划分为有信息的尖峰模式的参考。
