fMRI investigation of monocular pattern rivalry

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Visual Perception

Background:

• Monocular pattern rivalry involves alternating perceptions of composite images presented to both eyes.
• Previous research identified a widespread brain network involved in various forms of perceptual bistability.

Purpose of the Study:

• To investigate brain activity using fMRI during monocular rivalry.
• To compare neural responses to simple grating rivalry versus complex object rivalry.
• To determine if object rivalry differentially engages category-specific visual cortex.

Main Methods:

• Functional magnetic resonance imaging (fMRI) at 3 Tesla was employed.
• Participants viewed either grating or face/house composite stimuli under passive viewing or active task conditions.
• Stimuli were matched for luminance, contrast, and color; a non-rivalrous control was used for baseline comparison.

Main Results:

• Grating rivalry activated extrastriate cortex, parietal, and frontal regions compared to control.
• Object rivalry showed greater activation in extrastriate areas (V3, V3A, FFA, PPA) than grating rivalry.
• FFA and PPA activity correlated with dominant face or house percepts, respectively, during object rivalry.

Conclusions:

• Monocular rivalry, even with simple stimuli, recruits a large, distributed brain network.
• Complex object rivalry preferentially engages extrastriate visual cortex, including object-category-specific areas.
• Attentional fluctuations in monocular rivalry can drive category-specific cortical activity without complete image suppression.