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Brain Plasticity associated with Predictive Masking and Glaucoma
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Glaucoma is a disease resulting from damage at the optic nerve, the “highway” through
which visual information travels from the retina towards the visual brain. Such lesion
deprives the visual cortex of the regular input, causing interruptions within the visual
field – scotoma. However, even when such lesions occur, perception remains stable as
the human visual system perceptually masks the insult with the visual features of nearby
regions of the visual field. To unravel the neural mechanisms by which this remarkable
capacity occurs in glaucomatous individuals, we used functional magnetic resonance
imaging (fMRI) and neural modelling to track changes in cortical population receptive
fields (pRFs). We found that visual neurons from early visual areas (V1-3) expanded their
pRFs both inside and at the vicinity of the lesion. V1 pRFs also shifted their preferred
central position towards the outside of the scotoma. By doing so, neural populations
were able to process information from spared visual field, consistent with the notion of
predictive masking. In contrast, well-sighted observers did not show similar patterns of
neural activity in response to the introduction of an artificial scotoma (AS). Our findings
provide evidence of enduring cortical reorganization underlying the predictive spatial
masking of scotomas in glaucoma, meeting the contemporary view that early visual areas
of the adult human brain retain plastic mechanisms. Furthermore, the involvement of
the brain suggests that glaucoma pathogenesis goes beyond the eye.
Descrição
Palavras-chave
glaucoma masking population receptive field reorganization fMRI