Department of Psychiatry and Psychotherapy, Campus Charité Mitte, Charité-Universitätsmedizin Berlin, Berlin, Germany; Berlin Center for Advanced Neuroimaging, Charité - Universitätsmedizin Berlin, Germany.
Department of Psychiatry and Psychotherapy, Campus Charité Mitte, Charité-Universitätsmedizin Berlin, Berlin, Germany; International Max Planck Research School for Neuroscience, University of Göttingen, Germany.
Neuroimage. 2018 May 1;171:190-198. doi: 10.1016/j.neuroimage.2017.12.094. Epub 2017 Dec 30.
The phenomenon of bistable perception, in which perception alternates spontaneously despite constant sensory stimulation, has been particularly useful in probing the neural bases of conscious perception. The study of such bistability requires access to the observer's perceptual dynamics, which is usually achieved via active report. This report, however, constitutes a confounding factor in the study of conscious perception and can also be biased in the context of certain experimental manipulations. One approach to circumvent these problems is to track perceptual alternations using signals from the eyes or the brain instead of observers' reports. Here we aimed to optimize such decoding of perceptual alternations by combining eye and brain signals. Eye-tracking and functional magnetic resonance imaging (fMRI) was performed in twenty participants while they viewed a bistable visual plaid motion stimulus and reported perceptual alternations. Multivoxel pattern analysis (MVPA) for fMRI was combined with eye-tracking in a Support vector machine to decode participants' perceptual time courses from fMRI and eye-movement signals. While both measures individually already yielded high decoding accuracies (on average 86% and 88% correct, respectively) classification based on the two measures together further improved the accuracy (91% correct). These findings show that leveraging on both fMRI and eye movement data may pave the way for optimized no-report paradigms through improved decodability of bistable motion perception and hence for a better understanding of the neural correlates of consciousness.
双稳态感知现象，即感知尽管受到持续的感官刺激仍会自发地交替，这在探究意识感知的神经基础方面特别有用。对这种双稳态的研究需要获取观察者的感知动态，这通常是通过主动报告来实现的。然而，这种报告在意识感知的研究中构成了一个混杂因素，并且在某些实验操作的背景下也可能存在偏差。一种规避这些问题的方法是使用眼睛或大脑的信号来跟踪感知的交替，而不是依赖观察者的报告。在这里，我们旨在通过结合眼动和脑信号来优化这种感知交替的解码。二十名参与者在观看双稳态视觉格子运动刺激并报告感知交替时接受了眼动追踪和功能磁共振成像（fMRI）。对 fMRI 进行了多体素模式分析（MVPA），并与眼动追踪相结合，在支持向量机中对参与者的 fMRI 和眼动信号的感知时间历程进行解码。尽管这两种测量方法本身已经产生了很高的解码准确性（平均分别为 86%和 88%正确），但基于这两种测量方法的分类进一步提高了准确性（91%正确）。这些发现表明，利用 fMRI 和眼动数据可以通过提高双稳态运动感知的可解码性，为优化无报告范式铺平道路，从而更好地理解意识的神经相关性。
