Human sensory cortex structure and top-down controlling brain network determine individual differences in perceptual alternations.

Bistable perception is a type of subjective perception that spontaneously alternates between two perceptual interpretations of an ambiguous sensory input. Past functional magnetic resonance imaging (fMRI) studies have examined the activation patterns underlying bistable perception, yet the variability between individuals in the alternations is not well understood. Therefore, voxel-based morphometry (VBM) was introduced in this study to correlate the GM of the sensory cortex with the alternations of Rubin face-vase illusion in a large group of young adults. We found that the GM volume and density (GMV/GMD) of the left fusiform face area (FFA) were significantly positively correlated with the alternations. Next, Granger causality analysis (GCA) was introduced to investigate the top-down modulation from high-level areas to the sensory cortex using resting-state fMRI data. Correlations between the perceptual alternations and Granger causalities showed that the top-down modulations from high-level brain regions, such as the superior parietal lobule (SPL) to the left FFA, were positive. Together, these findings indicated that the anatomical structure of the face-selective area may determine individual alternations of the Rubin face-vase illusion. This process may be controlled by a high-level cortex associated with attentional modulation, such as the SPL or Posterior Cingulate Cortex (PCC).