Visual Perception Laboratory, Department of Psychiatry and Psychotherapy, Charité Universitätsmedizin, 10117 Berlin, Germany, and Department of Psychology, Humboldt-Universität zu Berlin, 10099 Berlin, Germany.
J Neurosci. 2013 Oct 2;33(40):16009-15. doi: 10.1523/JNEUROSCI.1418-13.2013.
During bistable vision, perception oscillates between two mutually exclusive percepts despite constant sensory input. Greater BOLD responses in frontoparietal cortex have been shown to be associated with endogenous perceptual transitions compared with "replay" transitions designed to closely match bistability in both perceptual quality and timing. It has remained controversial, however, whether this enhanced activity reflects causal influences of these regions on processing at the sensory level or, alternatively, an effect of stimulus differences that result in, for example, longer durations of perceptual transitions in bistable perception compared with replay conditions. Using a rotating Lissajous figure in an fMRI experiment on 15 human participants, we controlled for potential confounds of differences in transition duration and confirmed previous findings of greater activity in frontoparietal areas for transitions during bistable perception. In addition, we applied dynamic causal modeling to identify the neural model that best explains the observed BOLD signals in terms of effective connectivity. We found that enhanced activity for perceptual transitions is associated with a modulation of top-down connectivity from frontal to visual cortex, thus arguing for a crucial role of frontoparietal cortex in perceptual transitions during bistable perception.
在双稳态视觉中，尽管存在持续的感觉输入，感知仍会在两种相互排斥的知觉之间来回振荡。与旨在在知觉质量和时间上与双稳态紧密匹配的“回放”转换相比，前顶叶皮层中更大的 BOLD 反应与内源性知觉转换有关。然而，仍存在争议的是，这种增强的活动是否反映了这些区域对感觉水平处理的因果影响，或者相反，这是刺激差异的结果，例如，与回放条件相比，双稳态感知中的知觉转换持续时间更长。我们在 15 名人类参与者的 fMRI 实验中使用旋转的利萨如图形，控制了转换持续时间差异的潜在混杂因素，并证实了前顶叶区域在双稳态感知期间的转换中活动增加的先前发现。此外，我们应用动态因果建模来确定最佳解释观察到的 BOLD 信号的神经模型，就有效连接而言。我们发现，知觉转换的增强活动与从额叶到视觉皮层的自上而下连接的调制有关，因此，在前顶叶皮层在双稳态知觉中的知觉转换中起着关键作用。
