A cascade of attentional and default mode network dynamics following the resolution of perceptual ambiguity

The neural mechanisms underlying spontaneous perceptual switches during bistable perception, particularly the dynamic interplay between large-scale brain networks, remain incompletely understood. Here, using functional magnetic resonance imaging (fMRI) in six participants and a bistable kinetic depth effect (KDE) stimulus, we investigated the spatiotemporal dynamics of brain activity associated with spontaneous perceptual reversals compared to physically induced (replayed) switches. Leveraging a fine-grained functional brain parcellation (MD758) and time-resolved analysis including noise correlations, we identified a distributed network encompassing occipital (MT/MST, LOC), parietal (IPS), and frontal (FEF, IFC, DLPFC) regions showing differential activity during spontaneous versus replayed switches. This network topography qualitatively overlapped a prior review-derived synthesis of perceptual-switching regions. Temporal decomposition of the differential fMRI signal further revealed a characteristic network cascade after the perceptual report: positive dorsal attention (DAN) and visual (VIS) network contrasts peaked approximately 4 s after the report alongside a negative default mode network (DMN) contrast; a slower, more modest ventral attention (VAN)-frontoparietal (FPN) component was observed around 10 s post-report but was weak and is treated as preliminary. The early 4 s profile was recovered across raw-signal, PCA-denoised, and noise-correlation analyses (three related, not fully independent analyses), with the noise-correlation analysis indicating that it is not fully attributable to shared motor-report signals. These findings delineate the temporal sequence of network recruitment following spontaneous perceptual transitions and suggest that interplay between attentional control and default mode networks accompanies the resolution of perceptual ambiguity.