Interocular suppression in the primary visual cortex: a possible neural basis of binocular rivalry

Area of Science:

• Neuroscience
• Visual Perception
• Computational Neuroscience

Background:

• Binocular rivalry is a phenomenon where perception alternates between dissimilar images presented to each eye.
• Understanding the neural basis of binocular rivalry is crucial for explaining visual perception.
• Previous research suggested interocular interactions play a role, but the specific mechanisms were unclear.

Purpose of the Study:

• To investigate the physiological basis of alternating perceptual suppression in binocular rivalry.
• To examine the responses of neurons in the lateral geniculate nucleus (LGN) and primary visual cortex (area 17) to dissimilar visual stimuli.
• To determine the role of interocular interactions in binocular rivalry.

Main Methods:

• Studied cat LGN and area 17 neuronal responses to drifting gratings with varying orientation, spatial frequency, and contrast presented to each eye.
• Recorded neuronal activity under conditions simulating binocular rivalry.
• Analyzed interocular inhibitory interactions and their dependence on stimulus parameters.

Main Results:

• Nearly half of LGN neurons showed modest inhibitory interaction, independent of orientation differences.
• Monocularly driven units in area 17 layer 4 behaved similarly.
• The majority of binocular cortical cells exhibited suppression of responses when presented with dissimilar gratings to each eye, a non-linear interaction dependent on concurrent stimulation.

Conclusions:

• Perceptual dominance switches in binocular rivalry likely depend on interocular interactions within binocular neurons of the primary visual cortex.
• Intracortical inhibition between ocular dominance columns may contribute to these interactions.
• The spontaneous alternations in perceptual suppression during prolonged viewing require further investigation.