White matter plasticity following cataract surgery in congenitally blind patients

Abstract

The visual system develops abnormally when visual input is absent or degraded during a critical period early in life. Restoration of the visual input later in life is generally thought to have limited benefit because the visual system will lack sufficient plasticity to adapt to and utilize the information from the eyes. Recent evidence, however, shows that congenitally blind adolescents can recover both low-level and higher-level visual function following surgery. In this study, we assessed behavioral performance in both a visual acuity and a face perception task alongside longitudinal structural white matter changes in terms of fractional anisotropy (FA) and mean diffusivity (MD). We studied congenitally blind patients with dense bilateral cataracts, who received cataract surgery at different stages of adolescence. Our goal was to differentiate between age- and surgery-related changes in both behavioral performance and structural measures to identify neural correlates which might contribute to recovery of visual function. We observed surgery-related long-term increases of structural integrity of late-visual pathways connecting the occipital regions with ipsilateral fronto-parieto-temporal regions or homotopic contralateral areas. Comparison to a group of age-matched healthy participants indicated that these improvements went beyond the expected changes in FA and MD based on maturation alone. Finally, we found that the extent of behavioral improvement in face perception was mediated by changes in structural integrity in late visual pathways. Our results suggest that sufficient plasticity remains in adolescence to partially overcome abnormal visual development and help localize the sites of neural change underlying sight recovery.

Project Prakash: Merging Basic Science and Societal Service in Vision Research

“…However, given sufficient visual experience, the children transition to a more stereotypical step function, whereby they consistently reject non-faces, regardless of how face-like the pattern is. These improvements in face classification are associated with structural changes in the brain, including increased integrity of late visual pathways known to support face processing (Pedersini et al, 2023). Overall, these findings have implications for the innateness of sensitivity to faces (it seems to be experience-expectant), theories of plasticity and critical periods (some skills can be acquired even at a late age, though acquisition is protracted), and specific cues that are used for early categorization (graded to step function).…”

Altered visual cortex excitatory/inhibitory ratio following transient congenital visual deprivation in humans

“…These visual deficits in congenital cataract-reversal individuals have been attributed to altered neural development due to the absence of vision, as individuals who suffered from developmental cataracts do not typically display a comparable severity of impairments (Lewis & Maurer, 2009; Sourav et al, 2020). While extant literature reported correlations between structural changes and behavioral outcomes in congenital cataract-reversal individuals (Feng et al, 2021; Guerreiro et al, 2015; Hölig et al, 2023; Pedersini et al, 2023), functional brain imaging (Heitmann et al, 2023; Raczy et al, 2022) and electrophysiological research (Bottari et al, 2016; Ossandón et al, 2023; Pant et al, 2023; Pitchaimuthu et al, 2021) have started to unravel the neural mechanisms which rely on visual experience during sensitive periods for development.…”