Interocular rivalry revealed in the human cortical blind-spot representation

Area of Science:

• Neuroscience
• Cognitive Science
• Visual Perception

Background:

• Conscious vision requires understanding how the brain selects visual signals for awareness.
• Binocular rivalry occurs when different images presented to each eye compete for conscious perception.
• The neural basis of binocular rivalry (pattern vs. channel competition) remains debated.

Purpose of the Study:

• To investigate whether binocular rivalry arises from interocular competition.
• To determine the role of the primary visual cortex (V1) in mediating conscious visual selection during rivalry.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was used to measure brain activity.
• Activity was examined in a monocular region of V1 corresponding to the blind spot.
• Participants viewed rivalrous gratings at the blind spot location and reported their dominant percept.

Main Results:

• The monocular blind-spot representation in V1 showed increased activation when the ipsilateral eye's image was perceived.
• This representation was suppressed when the blind-spot eye's image dominated perception.
• These rivalry-related neural responses were comparable in magnitude to actual perceptual alternations.

Conclusions:

• The findings provide the first physiological evidence that interocular competition underlies binocular rivalry.
• Primary visual cortex (V1) plays a crucial role in the selection and expression of conscious visual information.
• Binocular rivalry may be fully resolved within monocular visual cortex.