Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada.
Proc Natl Acad Sci U S A. 2010 Dec 21;107(51):21973-8. doi: 10.1073/pnas.1008587107. Epub 2010 Dec 3.
Spike trains commonly exhibit interspike interval (ISI) correlations caused by spike-activated adaptation currents. Here we investigate how the dynamics of adaptation currents can represent spike pattern information generated from stimulus inputs. By analyzing dynamical models of stimulus-driven single neurons, we show that the activation states of the correlation-inducing adaptation current are themselves statistically independent from spike to spike. This paradoxical finding suggests a biophysically plausible means of information representation. We show that adaptation independence is elicited by input levels that produce regular, non-Poisson spiking. This adaptation-independent regime is advantageous for sensory processing because it does not require sensory inferences on the basis of multivariate conditional probabilities, reducing the computational cost of decoding. Furthermore, if the kinetics of postsynaptic activation are similar to the adaptation, the activation state information can be communicated postsynaptically with no information loss, leading to an experimental prediction that simple synaptic kinetics can decorrelate the correlated ISI sequence. The adaptation-independence regime may underly efficient weak signal detection by sensory afferents that are known to exhibit intrinsic correlated spiking, thus efficiently encoding stimulus information at the limit of physical resolution.
尖峰序列通常表现出由尖峰激活适应电流引起的尖峰间间隔 (ISI) 相关性。在这里，我们研究了适应电流的动力学如何能够代表由刺激输入生成的尖峰模式信息。通过分析受刺激驱动的单个神经元的动力学模型，我们表明，引起相关性的适应电流的激活状态本身在尖峰到尖峰之间是统计独立的。这个自相矛盾的发现表明了一种具有生物物理合理性的信息表示方式。我们表明，适应独立性是由产生规则的、非泊松尖峰的输入水平引起的。这种适应独立性机制有利于感觉处理，因为它不需要基于多元条件概率的感觉推断，从而降低了解码的计算成本。此外，如果突触后激活的动力学类似于适应，那么激活状态信息可以在突触后传递而不会有信息丢失，这导致了一个实验预测，即简单的突触动力学可以使相关的 ISI 序列去相关。适应独立性机制可能是感觉传入纤维有效检测弱信号的基础，已知感觉传入纤维表现出内在的相关尖峰活动，从而在物理分辨率的极限处有效地编码刺激信息。
