Stimulating both eyes with matching stimuli enhances V1 responses
Blake A. Mitchell,
Kacie Dougherty,
Jacob A. Westerberg,
Brock M. Carlson,
Loïc Daumail,
Alexander Maier,
Michele A. Cox
Affiliations
Blake A. Mitchell
Department of Psychology, Vanderbilt Brain Institute, Vanderbilt Vision Research Center, Vanderbilt University, Nashville, TN 37240, USA; Corresponding author
Kacie Dougherty
Princeton Neuroscience Institute, Princeton University, Princeton, NJ 08544, USA
Jacob A. Westerberg
Department of Psychology, Vanderbilt Brain Institute, Vanderbilt Vision Research Center, Vanderbilt University, Nashville, TN 37240, USA
Brock M. Carlson
Department of Psychology, Vanderbilt Brain Institute, Vanderbilt Vision Research Center, Vanderbilt University, Nashville, TN 37240, USA
Loïc Daumail
Department of Psychology, Vanderbilt Brain Institute, Vanderbilt Vision Research Center, Vanderbilt University, Nashville, TN 37240, USA
Alexander Maier
Department of Psychology, Vanderbilt Brain Institute, Vanderbilt Vision Research Center, Vanderbilt University, Nashville, TN 37240, USA
Michele A. Cox
Center for Visual Science, University of Rochester, Rochester, NY 14627, USA; Corresponding author
Summary: Neurons in the primary visual cortex (V1) of primates play a key role in combining monocular inputs to form a binocular response. Although much has been gleaned from studying how V1 responds to discrepant (dichoptic) images, equally important is to understand how V1 responds to concordant (dioptic) images in the two eyes. Here, we investigated the extent to which concordant, balanced, zero-disparity binocular stimulation modifies V1 responses to varying stimulus contrast using intracranial multielectrode arrays. On average, binocular stimuli evoked stronger V1 activity than their monocular counterparts. This binocular facilitation scaled most proportionately with contrast during the initial transient. As V1 responses evolved, additional contrast-mediated dynamics emerged. Specifically, responses exhibited longer maintenance of facilitation for lower contrast and binocular suppression at high contrast. These results suggest that V1 processes concordant stimulation of both eyes in at least two sequential steps: initial response enhancement followed by contrast-dependent control of excitation.
