Visual brain plasticity induced by central and peripheral visual field loss

Abstract

Disorders that specifically affect central and peripheral vision constitute invaluable models to study how the human brain adapts to visual deafferentation. We explored cortical changes after the loss of central or peripheral vision. Cortical thickness (CoTks) and resting-state cortical entropy (rs-CoEn), as a surrogate for neural and synaptic complexity, were extracted in 12 Stargardt macular dystrophy, 12 retinitis pigmentosa (tunnel vision stage), and 14 normally sighted subjects. When compared to controls, both groups with visual loss exhibited decreased CoTks in dorsal area V3d. Peripheral visual field loss also showed a specific CoTks decrease in early visual cortex and ventral area V4, while central visual field loss in dorsal area V3A. Only central visual field loss exhibited increased CoEn in LO-2 area and FG1. Current results revealed biomarkers of brain plasticity within the dorsal and the ventral visual streams following central and peripheral visual field defects.Electronic supplementary materialThe online version of this article (10.1007/s00429-018-1700-7) contains supplementary material, which is available to authorized users.

Higher Dementia Incidence in Older Adults with Poor Visual Acuity

“…One possible explanation for the difference in findings is that we did not assess the onset, duration, severity and treatment of these ophthalmic conditions in this study. Previous studies show that correcting cataract with surgery is associated with better cognitive performance and increased grey matter volume in the visual cortex ( 36–40 ). With our data also showing that moderate-to-severe, but not mild, visual impairment is associated with higher risk of dementia, it would be of interest to further examine whether early treatment of poor vision might help delay or prevent clinical manifestation of dementia in older adults.…”

Structural evaluation in inherited retinal diseases

“…122 Importantly, several MRI studies have described a degree of plasticity/remodelling following visual field defects in RCD or MD, and also with congenital visual impairment, including in ACHM. [123][124][125] The remapping of the primary visual cortex (V1) consists of a shift of central retinal inputs to more peripheral locations in V1, and this phenomenon was found to be larger in patients with more constricted visual fields. 125 However, it was noted that individuals with RCD did not have marked structural differences compared with controls (changes in white matter were mild); but in contrast, individuals with early-onset visual loss had thickened striate cortical and grey matter.…”

Visual Cortical Plasticity in Retinitis Pigmentosa

“…Two studies 28,29 have compared BOLD responses in the visual cortex before and after retinal prosthetic implants and demonstrated that a degree of visual cortical plasticity is indeed possible in adults who have experienced complete blindness for several years. Evidence for plasticity is also available for adult patients with residual central vision, whose occipital cortex undergoes an apparent reorganization of retinotopic maps; in these patients, the representation of the central visual field spreads over the peripheral region, which is deprived of its normal visual input 30,31 ; there are also structural changes, affecting cortical thickness 32 ; however, the mechanisms underlying this reorganization are debated. 33 In addition, these patients show evidence for cross-modal plasticity, 28 whereby the deafferented peripheral representation may become responsive to nonvisual signals, and these signals may interact competitively with visual signals from the spared visual field.…”