Visual Cortical Plasticity in Retinitis Pigmentosa

Abstract

PURPOSE. Retinitis pigmentosa is a family of genetic diseases inducing progressive photoreceptor degeneration. There is no cure for retinitis pigmentosa, but prospective therapeutic strategies are aimed at restoring or substituting retinal input. Yet, it is unclear whether the visual cortex of retinitis pigmentosa patients retains plasticity to react to the restored visual input. METHODS. To investigate short-term visual cortical plasticity in retinitis pigmentosa, we tested the effect of short-term (2 hours) monocular deprivation on sensory ocular dominance (measured with binocular rivalry) in a group of 14 patients diagnosed with retinitis pigmentosa with a central visual field sparing greater than 208 in diameter. RESULTS. After deprivation most patients showed a perceptual shift in ocular dominance in favor of the deprived eye (P < 0.001), as did control subjects, indicating a level of visual cortical plasticity in the normal range. The deprivation effect correlated negatively with visual acuity (r ¼ À0.63, P ¼ 0.015), and with the amplitude of the central 188 focal electroretinogram (r ¼ À0.68, P ¼ 0.015) of the deprived eye, revealing that in retinitis pigmentosa stronger visual impairment is associated with higher plasticity. CONCLUSIONS. Our results provide a new tool to assess the ability of retinitis pigmentosa patients to adapt to altered visual inputs, and suggest that in retinitis pigmentosa the adult brain has sufficient short-term plasticity to benefit from prospective therapies.

Some psychophysical tasks measure ocular dominance plasticity more reliably than others

“…As shown in Figure 8 , however, we used our raw data from baseline and postpatching to directly compute the effect size to be more precise. Also, many studies have a smaller sample size than ours ( n = 15), so the reported effect size might have been more prone to a few outliers who displayed an exceptionally large change in sensory eye balance ( Bai, Dong et al, 2017 ; Binda, Kurzawski et al, 2018 ; Binda & Lunghi, 2017 ; Kim, Kim et al, 2017 ; Lo Verde, Morrone et al, 2017 ; Lunghi, Burr et al, 2011 ; Lunghi, Burr et al, 2013 ; Lunghi, Galli-Resta et al, 2019 ; Ramamurthy & Blaser, 2018 ; Wang, McGraw et al, 2020 ). In addition, although applying a diffuser to one eye is a common method to monocularly deprive its visual input, the methods of monocular deprivation can differ across studies.…”

Residual Visual Responses in Patients With Retinitis Pigmentosa Revealed by Functional Magnetic Resonance Imaging

“…34). In a separate work by our group, we found that RP patients with sparing of the central visual field have increased visual plasticity, stronger in patients with greater deficits, suggesting that cortical gating might be active throughout the evolution of the disease35 and it might be the consequence of cross-modal (or maladaptive) plasticity.…”

Visual Cortex Engagement in Retinitis Pigmentosa

“…Although general alterations of brain activity have been described in individuals with RP [27][28][29] and animal models [30,31], the impact of retinal degeneration on cortical circuits is largely unknown. Only recently, it has been shown that the adult brain of RP patients retains a good level of short-term plasticity [32], and we have reported that visual cortical circuits in rd10 mice preserve their capability of input-dependent remodeling until an advanced stage of retinal damage [33].…”