Claudia Lunghi

1er juin 2018

Laboratoire des Systèmes Perceptifs, ENS, Paris

Ocular dominance plasticity in adult humans

invitée par Anna Montagnini

bstract : Neuroplasticity is a fundamental property of the nervous system that is maximal early in life, within a specific temporal window called critical period. However, it is still unclear to which extent neuroplasticity persists in adulthood. We have recently revealed residual ocular dominance plasticity in humans by showing that short-term monocular deprivation unexpectedly boosts the deprived eye in adults. After 150 minutes of monocular deprivation, the deprived eye strongly dominates visual perception during binocular rivalry (a form of perceptual bistability that engages strong competition between the monocular signals), reflecting homeostatic plasticity. This effect lasts for up to 3 hours after re-exposure to binocular vision and is accompanied by a boost in apparent contrast. Monocular deprivation also alters the earliest components of the Visual Evoked Potential both increasing the deprived eye and decreasing non-deprived eye responses to visual stimulation. Importantly, we have further shown that GABA concentration (measured by means of 7-Tesla Magnetic Resonance Spectroscopy) decreases in the adult primary visual cortex after short-term monocular deprivation and that, across subjects, the decrease in GABA correlates with the perceptual boost of the deprived eye during binocular rivalry, suggesting a critical role for GABAergic inhibition in triggering visual plasticity. Finally, we have found that this form of homeostatic plasticity can be influenced by extra-retinal inputs (physical exercise) and that short-term deprivation of the amblyopic eye combined with physical exercise can promote the recovery of visual function in adult anisometropic patients. Taken together, these results challenge the classical view of a hard-wired adult visual cortex, indicating that the adult visual cortex retains a degree of ocular dominance plasticity higher than previously thought.

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