Belitski Andrei, Panzeri Stefano, Magri Cesare, Logothetis Nikos K, Kayser Christoph
Max Planck Institute for Biological Cybernetics, Spemannstrasse 38, 72076, Tübingen, Germany.
J Comput Neurosci. 2010 Dec;29(3):533-45. doi: 10.1007/s10827-010-0230-y. Epub 2010 Mar 16.
Studies analyzing sensory cortical processing or trying to decode brain activity often rely on a combination of different electrophysiological signals, such as local field potentials (LFPs) and spiking activity. Understanding the relation between these signals and sensory stimuli and between different components of these signals is hence of great interest. We here provide an analysis of LFPs and spiking activity recorded from visual and auditory cortex during stimulation with natural stimuli. In particular, we focus on the time scales on which different components of these signals are informative about the stimulus, and on the dependencies between different components of these signals. Addressing the first question, we find that stimulus information in low frequency bands (<12 Hz) is high, regardless of whether their energy is computed at the scale of milliseconds or seconds. Stimulus information in higher bands (>50 Hz), in contrast, is scale dependent, and is larger when the energy is averaged over several hundreds of milliseconds. Indeed, combined analysis of signal reliability and information revealed that the energy of slow LFP fluctuations is well related to the stimulus even when considering individual or few cycles, while the energy of fast LFP oscillations carries information only when averaged over many cycles. Addressing the second question, we find that stimulus information in different LFP bands, and in different LFP bands and spiking activity, is largely independent regardless of time scale or sensory system. Taken together, these findings suggest that different LFP bands represent dynamic natural stimuli on distinct time scales and together provide a potentially rich source of information for sensory processing or decoding brain activity.
分析感觉皮层处理过程或试图解码大脑活动的研究通常依赖于不同电生理信号的组合，如局部场电位（LFP）和脉冲活动。因此，了解这些信号与感觉刺激之间以及这些信号不同成分之间的关系非常重要。我们在此对在自然刺激下从视觉和听觉皮层记录的LFP和脉冲活动进行分析。特别是，我们关注这些信号的不同成分在哪些时间尺度上对刺激具有信息性，以及这些信号不同成分之间的依赖性。针对第一个问题，我们发现低频带（<12 Hz）中的刺激信息很高，无论其能量是在毫秒尺度还是秒尺度上计算。相比之下，较高频段（>50 Hz）中的刺激信息与尺度有关，当能量在几百毫秒内平均时更大。事实上，对信号可靠性和信息的综合分析表明，即使考虑单个或少数周期，慢LFP波动的能量也与刺激密切相关，而快LFP振荡的能量只有在多个周期平均时才携带信息。针对第二个问题，我们发现不同LFP频段以及不同LFP频段和脉冲活动中的刺激信息在很大程度上是独立的，无论时间尺度或感觉系统如何。综上所述，这些发现表明不同的LFP频段在不同的时间尺度上代表动态自然刺激，并共同为感觉处理或解码大脑活动提供了潜在丰富的信息来源。
