Short-term plasticity in the human visual thalamus

Abstract

While there is evidence that the visual cortex retains a potential for plasticity in adulthood, less is known about the subcortical stages of visual processing. Here we asked whether short-term ocular dominance plasticity affects the human visual thalamus. We addressed this question in normally sighted adult humans, using ultra-high field (7T) magnetic resonance imaging combined with the paradigm of short-term monocular deprivation. With this approach, we previously demonstrated transient shifts of perceptual eye dominance and ocular dominance in visual cortex (Binda et al., 2018). Here we report evidence for short-term plasticity in the ventral division of the pulvinar (vPulv), where the deprived eye representation was enhanced over the non-deprived eye. This ventral-pulvinar plasticity was similar as previously seen in visual cortex and it was correlated with the ocular dominance shift measured behaviorally. In contrast, there was no effect of monocular deprivation in two adjacent thalamic regions: dorsal pulvinar (dPulv), and Lateral Geniculate Nucleus (LGN). We conclude that the visual thalamus retains potential for short-term plasticity in adulthood; the plasticity effect differs across thalamic subregions, possibly reflecting differences in their cortico-fugal connectivity.

Sensory Eye Dominance Plasticity in the Human Adult Visual Cortex

“…To our knowledge, changes of eye-specific responses in the LGN has only been demonstrated in rodents that have been monocularly deprived for a week (Jaepel et al, 2017). A recent functional brain imaging (fMRI) study involving visually healthy human adults did not observe changes in LGN after 2-hours of monocular deprivation (Kurzawski et al, 2022). It is worth noting, however that the neural mechanisms underlying this kind of short-term plasticity may be different from those induced by a more extended period of monocular deprivation (Ramamurthy and Blaser, 2021) or binocular perceptual training.…”

Negligible contribution of adaptation of ocular opponency neurons to the effect of short-term monocular deprivation

“…One failed in binocular fusion in the EEG pre-test, thus also quit from the rest of the experiment. The sample size was predetermined based on previous studies in this field ( Lunghi et al, 2015 ; Binda et al, 2018 ; Lyu et al, 2020 ; Virathone et al, 2021 ; Baldwin et al, 2022 ; Kurzawski et al, 2022 ). All participants were naive to the experimental hypotheses, had normal or corrected-to-normal vision.…”

Mutual interaction between Visual Homeostatic Plasticity and Sleep in Adult Humans

“…This counterintuitive result, consistent with homeostatic plasticity, is interpreted as a compensatory adjustment of contrast gain in response to deprivation. The deprived eye boost is observed also at the neural level, as revealed by EEG 28 , MEG 29 and fMRI 30,31 and, importantly, it is mediated by a decrease of GABAergic inhibition in the primary visual cortex 32 . The effect of short-term MD decays within 90 minutes from eye-patch removal 25,27 .…”

“…The artifact-free EEG segments analysed for estimating power band content in five frequency bands of interest were considered: theta (4-8 Hz), alpha (8)(9)(10)(11)(12), low beta (12)(13)(14)(15)(16)(17)(18)(19)(20), high beta (20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30) and gamma (30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43)(44)(45). Power densities were estimated by applying a Hamming-windowed FFT on 4 sec consecutive EEG segments and log-transformed (dB).…”