Mease Rebecca A, Kuner Thomas, Fairhall Adrienne L, Groh Alexander
Department of Neurosurgery, Technische Universität München, Munich 81675, Germany; Neurobiology and Behavior Graduate Program, University of Washington, Seattle, WA 98195, USA.
Department of Functional Neuroanatomy, Heidelberg University, Heidelberg 69120, Germany.
Cell Rep. 2017 May 9;19(6):1130-1140. doi: 10.1016/j.celrep.2017.04.050.
High-frequency "burst" clusters of spikes are a generic output pattern of many neurons. While bursting is a ubiquitous computational feature of different nervous systems across animal species, the encoding of synaptic inputs by bursts is not well understood. We find that bursting neurons in the rodent thalamus employ "multiplexing" to differentially encode low- and high-frequency stimulus features associated with either T-type calcium "low-threshold" or fast sodium spiking events, respectively, and these events adapt differently. Thus, thalamic bursts encode disparate information in three channels: (1) burst size, (2) burst onset time, and (3) precise spike timing within bursts. Strikingly, this latter "intraburst" encoding channel shows millisecond-level feature selectivity and adapts across statistical contexts to maintain stable information encoded per spike. Consequently, calcium events both encode low-frequency stimuli and, in parallel, gate a transient window for high-frequency, adaptive stimulus encoding by sodium spike timing, allowing bursts to efficiently convey fine-scale temporal information.
高频“爆发式”尖峰簇是许多神经元的一种通用输出模式。虽然爆发式放电是跨动物物种的不同神经系统中普遍存在的一种计算特征，但爆发式放电对突触输入的编码方式尚未得到很好的理解。我们发现，啮齿动物丘脑的爆发式放电神经元采用“复用”方式，分别对与T型钙“低阈值”或快速钠尖峰事件相关的低频和高频刺激特征进行差异编码，并且这些事件的适应方式不同。因此，丘脑爆发式放电在三个通道中编码不同的信息：（1）爆发式放电的大小，（2）爆发式放电的起始时间，以及（3）爆发式放电内精确的尖峰时间。引人注目的是，后一个“爆发式放电内”编码通道表现出毫秒级的特征选择性，并在不同的统计背景下进行适应，以保持每个尖峰编码的稳定信息。因此，钙事件既编码低频刺激，又同时为通过钠尖峰时间进行的高频适应性刺激编码打开一个瞬态窗口，使爆发式放电能够有效地传递精细尺度的时间信息。
