Investigating the human binocular visual system using multi-modal magnetic resonance imaging

titleInvestigating the human binocular visual system using multi-modal magnetic resonance imaging
start_date2024/07/09
schedule14h30-16h30
onlineno
location_infosalle Ribot
summarySeeing in stereoscopic depth relies on the slight differences in the images in the two eyes resulting from their horizonal separation. As the inputs from the eyes are first combined in the primary visual cortex (V1), human brain imaging can be used to investigate the earliest stages of processing. To perceive depth, binocular neurons in V1 need balanced input from the two eyes, likely established by mutual inhibition, whereby activation of one eye inhibits the other eye. Thus, when input from the two eyes is comparable, both will contribute equally to binocular vision to promote 3D vision. However, if input from one eye is consistently weaker, the other eye may dominate, a situation that can lead to amblyopia. I will describe MRI work using magnetic resonance spectroscopy indicating a role for inhibitory neurotransmitter GABA in binocular vision and eye dominance. This is the case for short term interventions as well as normal variability between people. I will then present two studies that investigate how population receptive field (pRF) mapping can determine the selectivity of cortical areas to binocular disparity. In the first study we show that V1 pRFs measured with a disparity-defined stimulus are larger than those generated by stimuli that do not require binocular interaction. Secondly, using pRF mapping in the depth plane, we show a relationship between the preferred depth and width of the tuning curve, such that voxels preferring zero disparity have narrower tuning curves. The ability to understand the mechanisms underlying human binocular vision raises the possibility of manipulating neural activity levels to improve function in those with impaired binocular vision.
responsiblesMamassian

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submittedpublished2024/06/13 10:37 UTC
speakers
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Event #1293119 - created on 2024/05/21