McGill Vision Research, McGill University, Montreal, QC, Canada; Research Institute of the McGill University Health Centre, Montreal, QC, Canada.
Neuroimage. 2020 Nov 1;221:117010. doi: 10.1016/j.neuroimage.2020.117010. Epub 2020 Jun 4.
Prototypical brain responses describe similarity in neural representations between subjects in response to a natural stimulus. During natural movie viewing, for example, inter-subject correlation (ISC) measured by fMRI is high in visual areas (Hasson et al., 2004). But the electrophysiological basis for this fMRI ISC has been controversial. Previous reports have only found ISC in low frequency bands-below 12 Hz (Chang et al., 2015). These findings stand in contrast to reports that gamma band oscillations-30 to 90 Hz-are highly stimulus-driven in visual cortex (Perry et al., 2015). To resolve this discrepancy, we carried out both ISC estimation and a novel inter-subject representational correlation analysis across six frequency bands extracted from MEG data of 24 subjects who each viewed four 5-min clips of an underwater documentary. Region-of-interest-based and vertex-based temporal ISC estimates confirmed that low-frequency bands are significantly synchronized in visual areas and that gamma band has low temporal correlation. We also found the representational geometry of movie scenes were related to structural statistics from the stimuli. Crucially, our results show that the gamma band oscillations also reflect prototypical brain response in scene representations formed in response to naturalistic stimuli as revealed by inter-subject representational correlation.
原型大脑反应描述了在自然刺激下,不同个体对神经表现的相似性。例如,在观看自然电影时, fMRI 测量的个体间相关性 (ISC) 在视觉区域很高 (Hasson 等人,2004 年)。但这种 fMRI ISC 的电生理基础一直存在争议。以前的报告仅在低频带中发现了 ISC——低于 12 Hz (Chang 等人,2015 年)。这些发现与伽马波段振荡-30 到 90 Hz-在视觉皮层中高度受刺激驱动的报告形成鲜明对比 (Perry 等人,2015 年)。为了解决这一差异,我们对来自 24 名受试者的 MEG 数据进行了 ISC 估计和一种新的跨个体代表性相关分析,这些受试者每人观看了四段 5 分钟的水下纪录片剪辑。基于感兴趣区域和顶点的时间 ISC 估计证实,低频带在视觉区域中明显同步,并且伽马带具有低时间相关性。我们还发现电影场景的代表性几何形状与刺激的结构统计数据有关。至关重要的是,我们的结果表明,伽马波段振荡也反映了自然刺激下形成的场景表示中的原型大脑反应,这一点通过跨个体代表性相关得到了揭示。