Responses to conflicting binocular stimuli in mouse primary visual cortex

Area of Science:

• Neuroscience
• Vision Science
• Computational Neuroscience

Background:

• Binocular vision integrates information from two eyes to create a unified percept.
• Interocular disparities are crucial for depth perception (stereopsis) but can cause diplopia or rivalry if not processed correctly.
• The precise neural mechanisms governing the processing of binocular disparities in the visual cortex remain largely unknown.

Purpose of the Study:

• To investigate the neural mechanisms underlying the processing of two distinct types of binocular disparity: interocular phase disparity and interocular orientation disparity.
• To differentiate the neural circuit dynamics associated with these two disparity types in the mouse primary visual cortex (bV1).

Main Methods:

• Utilized a combination of in vivo electrophysiology (visually evoked potential (VEP) recordings, unit recordings) and 2-photon calcium imaging.
• Recorded neural activity in the binocular region of the mouse primary visual cortex (bV1) under dichoptic stimulation.
• Introduced spatial interocular phase disparities and interocular orientation disparities in grating stimuli.

Main Results:

• Interocular phase disparity reduced VEP magnitude by decreasing early neuronal firing (40-80 ms).
• Interocular orientation disparity also reduced VEP magnitude but was associated with increased late neuronal firing (100-200 ms) in excitatory and inhibitory neurons.
• Somatostatin-positive interneurons showed decreased activity in response to interocular orientation disparity.

Conclusions:

• Interocular phase differences appear to suppress bV1 responses primarily through feedforward thalamocortical pathways.
• Interocular orientation differences may prolong bV1 activity via disinhibition mediated by somatostatin-positive interneurons.
• These findings elucidate distinct neural strategies for processing different types of binocular visual information.