The dissociations of visual processing of “hole” and “no‐hole” stimuli: An functional magnetic resonance imaging study

INTRODUCTION: “Where to begin” is a fundamental question of vision. A “Global‐first” topological approach proposed that the first step in object representation was to extract topological properties, especially whether the object had a hole or not. Numerous psychophysical studies found that the hole (closure) could be rapidly recognized by visual system as a primitive property. However, neuroimaging studies showed that the temporal lobe (IT), which lied at a late stage of ventral pathway, was involved as a dedicated region. It appeared paradoxical that IT served as a key region for processing the early component of visual information. Did there exist a distinct fast route to transit hole information to IT? We hypothesized that a fast noncortical pathway might participate in processing holes. METHODS: To address this issue, a backward masking paradigm combined with functional magnetic resonance imaging (fMRI) was applied to measure neural responses to hole and no‐hole stimuli in anatomically defined cortical and subcortical regions of interest (ROIs) under different visual awareness levels by modulating masking delays. RESULTS: For no‐hole stimuli, the neural activation of cortical sites was greatly attenuated when the no‐hole perception was impaired by strong masking, whereas an enhanced neural response to hole stimuli in non‐cortical sites was obtained when the stimulus was rendered more invisible. CONCLUSIONS: The results suggested that whereas the cortical route was required to drive a perceptual response for no‐hole stimuli, a subcortical route might be involved in coding the hole feature, resulting in a rapid hole perception in primitive vision.