Skip to Main content Skip to Navigation
Theses

Cerebral plasticity following central and peripheral visual field loss : investigated through morphological and functional MRI

Abstract : Cerebral plasticity induced by visual loss represents a poorly understood field of neuroscience, with numerous questions that don’t yet have an answer. Central and peripheral vision, the evolutionary compromise between spatial resolution and the sampled space volume, are processed in distinct areas of the brain. Understanding the impact of vision loss in theses regions, is of utmost interest for the study of visual brain. Herein, in two models of retinal disorders affecting central and peripheral vision (namely Stargardt macular dystrophy and retinitis pigmentosa), we specifically investigated the effects of the central and peripheral visual loss on brain morphology and its functional connectivity. 1. Morphological plastic changes induced by central and peripheral visual loss. We explored the effects of visual loss on cortical thickness (CoTks) and cortical entropy (CoEn, marker of synaptic complexity) in the cytoarchytectonic regions of the occipital lobe. Central visual loss associated thinning in dorsal stream regions, while peripheral visual loss in early visual cortex (EVC) and regions belonging both to dorsal and ventral stream. Theses effects were unpredicted by the canonical view “central vision – ventral stream”, “peripheral vision – dorsal stream”. Normal CoEn in theses areas suggests that synaptic complexity is preserved in the remaining networks. Only central visual field loss presented CoEn alterations, namely an increase in areas involved in object recognition, that likely reflects a synaptic complexity enhancement in response to the loss of the high spatial resolution of central vision. The gain in synaptic complexity could mask neuronal loss due to deafferentation and may account for the CoTks normality. 2. Plastic changes in the functional connectivity of central and peripheral EVC. We explored and compared to normally afferented EVC, the functional connectivity of afferented and deafferented parts of EVC and found that central and peripheral visual loss induce different patterns of reorganization. Residually afferented early visual cortex reinforce local connections presumably to enhance the processing of altered visual input, while deafferented EVC strengthen long-range connections presumably to assist high-order functions. Combined structural and functional data indicate that areas with reduced CoTks superpose with several areas presenting reduced functional connectivity with the peripheral EVC and that areas with increased CoEn superpose with several areas presenting increased functional connectivity with afferented peripheral EVC. These data point that alterations of the sensory input to the peripheral field are more prone to induce plastic changes. Overview : Data in the current work provide an interesting perspective about the plasticity following central or peripheral visual field loss and show that it is more complex than the canonical model would have let to presume.
Document type :
Theses
Complete list of metadatas

Cited literature [632 references]  Display  Hide  Download

https://tel.archives-ouvertes.fr/tel-01919424
Contributor : Abes Star :  Contact
Submitted on : Monday, November 12, 2018 - 2:13:07 PM
Last modification on : Tuesday, October 20, 2020 - 11:32:44 AM
Long-term archiving on: : Wednesday, February 13, 2019 - 1:56:43 PM

File

2017PA066584.pdf
Version validated by the jury (STAR)

Identifiers

  • HAL Id : tel-01919424, version 1

Citation

Nicolae Sanda. Cerebral plasticity following central and peripheral visual field loss : investigated through morphological and functional MRI. Neurons and Cognition [q-bio.NC]. Université Pierre et Marie Curie - Paris VI, 2017. English. ⟨NNT : 2017PA066584⟩. ⟨tel-01919424⟩

Share

Metrics

Record views

209

Files downloads

37