Innovating Visual Perception: A Transformative Voyage with Neuroplasticity

Sankhajyoti Saha, M.Optom

Assistant Professor, NSHM Knowledge Campus, Kolkata, India

Editorial Assistant, Vision Science Academy

 

Vision Science Academy Exclusive

Change is the only persistence of the universe, a verse in Bhagavad Gita says. In competence, adaptation is the essential essence of this change. Neuroplasticity cites the prosperity of the brain to accept the consequences of its interrelation to change in the environment.  The human visual cortex manifests Neuroplasticity throughout perceptual learning, attention, and adaptation. Even an optically perfect stimulus is imperfect without retina-brain reciprocity.  Stimulating Neuroplasticity could be the new outlook in the field of vision science for illuminating better treatment outcomes.

The journey of our environmental awareness started when we responded first to the very first light stimulus – red, the color of the fetal environment. ^{(1) (2)}  Some animal models enlightened the concept of  melanoma-dependent fetal light response (fetal light stimulus concept) which eventually regulates eye development, especially retinal  vasculature formation to develop a clear optical path. ⁽³⁾

Structural Plasticity (alterations in the neuronal morphology) and Synaptic Plasticity are two recognized theories that constitute Neuroplasticity. Hebbian theory interprets the Synaptic Plasticity concept, where stronger and persistent stimulation in a presynaptic region exposes a greater efficacy from post synaptic environs. ⁽⁴⁾

Clinical Pearls

Mislaying visual acuity authorizes the brain to ingress a new pathway for the pursuit to conquer the visual loss. This is the field where the cortical reestablishment verily transpires. The CNS is a repeatedly changing structure, which expands and responds well to sensory modality loss and new-fangled perceptual learning processes. Cross plasticity and multi-modal plasticity theories collaborate to describe the conscription of visual cortical areas, for non-visual task, after cognitive visual impairment, which ultimately refrains to the balance alteration in the neural networks, due to the visual truancy, which  accredits the catalysing of preexisting pathways that were being reserved for vision. ⁽⁵⁾ Functional magnetic resonance imaging (fMRI), electroencephalography (EEG) and trans cranial magnetic stimulation (TMS) revealed an opinion which shows visual plasticity occurs at all stages of life in response to assorted sensory experience. ⁽⁴⁾

• Amblyopia can be considered a case resulting from lack of normal visual plasticity. In an amblyopic person, redoing a visually demanding task (perceptual learning) assists the visual attention resulting in cybernation of the task which eventually develops visual adaptation (in the form of visual acuity) that persists for a prolonged period. Hypothesis for video game playing with amblyopic eye has shown a promising result among the adult visual system, in terms of improvement in spatial frequency which is the core element of visual acuity. ⁽⁴⁾

An evidence which shows the improved vision in amblyopic adults highlights the cortical connections which are inhibited for some visual functions, indicating the existence of visual plasticity which can be assembled with rapid readaptation. ⁽⁴⁾ Though visual plasticity is limited within the critical period, the process of readaptation contains forms of learning and addiction-related processes.

• Patients with Retinitis Pigmentosa show a positive response after a short-term monocular deprivation; post deprivation results show significant increment in ocular dominance by the deprived eye. The result evinces that even after critical period, visual cortex (V1 area) maintains potential to plasticity acclimation to visual change, maintaining a slower switching rate between deprived and non-deprived eye aggregating binocular rivalry. ⁽⁶⁾

Future directions

Learning and adaptation is a frolic drive to intensify several forms of sensory plasticity by environmental direction, considering the visual system as a gold standard. We are heading towards a future where a person with no vision can adapt other sensory readaptation as a therapeutic regimen. Growing psycho-physical evidence illustrates improvement in olfactory plasticity  in blind persons with a lower threshold and higher awareness of olfactory domain, in comparison to a normal vision person. ⁽⁵⁾

Literatures support the role of visual cortical plasticity both in the presence and absence of visual impairment. Charles Bonnet Syndrome is a clinical example where a person experiences hallucination not only with psychiatric disorders, but with normal visual acuity as well. ⁽⁴⁾

This era gives you the chance to explore different approaches for neuro-degenerative visual impairment which is apotheosis than previously cogitated.

The next big question is: Are We Primed Enough?

 

References

1. Donovan, T., Dunn, K., Penman, A., Young, R. J., & Reid, V. M. (2020). Fetal eye movements in response to a visual stimulus. In Brain and Behavior (Vol. 10, Issue 8). Wiley. https://doi.org/10.1002/brb3.1676
2. What color is the inside of a womb? (2022, September 3). What Color Is the Inside of a Womb? https://yourfasttip.com/miscellaneous/what-color-is-the-inside-of-a-womb
3. Rao, S., Chun, C., Fan, J. et al. A direct and melanopsin-dependent fetal light response regulates mouse eye development. Nature 494, 243–246 (2013). https://doi.org/10.1038/nature11823
4. Martins Rosa, A., Silva, M. F., Ferreira, S., Murta, J., & Castelo-Branco, M. (2013). Plasticity in the human visual cortex: an ophthalmology-based perspective. BioMed research international, 2013, 568354. https://doi.org/10.1155/2013/568354
5. Silva, P. R., Farias, T., Cascio, F., Dos Santos, L., Peixoto, V., Crespo, E., Ayres, C., Ayres, M., Marinho, V., Bastos, V. H., Ribeiro, P., Velasques, B., Orsini, M., Fiorelli, R., de Freitas, M. R. G., & Teixeira, S. (2018). Neuroplasticity in visual impairments. Neurology international, 10(4), 7326. https://doi.org/10.4081/ni.2018.7326
6. Lunghi, C., Galli-Resta, L., Binda, P., Cicchini, G. M., Placidi, G., Falsini, B., & Morrone, M. C. (2019). Visual Cortical Plasticity in Retinitis Pigmentosa. Investigative ophthalmology & visual science, 60(7), 2753–2763. https://doi.org/10.1167/iovs.18-25750

The figure has been created by the author using AI tool (gencraft), which allows non-commercial use.