discussions

Is the loss of sensory systems normal?

Modern medical science has allowed people who have been blind for their entire life to have their sight restored. When sight is restored do you think that these people will immediately see in the same way as someone who has never lost their sight? What components of the visual system would affect what the person sees in this situation and how they interpret it? Respond to at least two of your classmates’ posts no later than Monday, Day 7.

Respond to two classmates

Respond to Classmate 1:

New systematic approaches have suggested that vision can somewhat be restored to those who earlier would have been blind for life. Nevertheless, experts at the University of Montreal and the University of Trento have learned that the rewiring of the senses that happens in the long-term blind's person brains indicates that optical recovery may never be complete. "We had the chance to examine the unique instance of a woman with defective eyesight following birth and whose sight abruptly restored in adulthood following the implantation of a Boston Keratoprosthesis in her right eye," explained Giulia Dormal, who led the research.  “Moschos goes on to say, "On one hand, our conclusions exhibit that the visual cortex keeps a particular level of flexibility -- that is the size to shift as a purpose of experience -- in an adult person with low sight since early life (Moschos, 2015). “On the other, we found that several months after the operation, the visual cortex had not recovered full, healthy functioning." The visual cortex is the part of the brain that processes information from our eyes.

Experts acknowledge that in cases of untreatable blindness, the occipital cortex -- that is the posterior part of the brain that is typically given to vision -- becomes sensitive to sound and touch to compensate for the loss of vision.  “According to the National Academies Press, "This essential brain reestablishment signifies a difficulty for people facing eye surgery to recover vision because the deprived and reconstructed occipital cortex may not be able to see anymore after having spent years in the dark (National Academies Press, 2016). To determine how much of a hurdle this may be, the researchers worked with the patient, a 50-year-old Quebec woman. They administered behavioral and neurophysiological measurements before and after the operation to track changes in her sight and brain anatomy and how her brain reacted to sights and sounds. It included taking MRI images as she performed several visual and auditory tasks and compared her scans with scans taken from people with healthy eyesight and untreatable blindness who had done the same tasks. We show that anatomical and functional reorganization of occipital regions were in this patient before the operation as a result of long-standing visual impairment, and visual recovery in adulthood can partly convert some reorganizations, said Oliver Collignon, who oversaw the study. "Because of significant improvements in visual restoration methods, such conclusions have serious clinical assumptions for the imminent result of blind individuals who are candidates to such interventions (National Academies Press, 2016).

“Thus, research implies that eye operation can lead to a particular result even when given in adulthood after a lifetime of deep-felt blindness. There is, nevertheless, an essential caution. "The recovery seen in the visual cortex that is highlighted by a reduction in auditory-driven responses and by an increase in both visually-driven responses and grey matter density with time is not total," Dormal describe (Moschos, 2015).Surely, auditory-driven responses still evidenced in some areas of the visual cortex even seven months after surgery, and these responses overlaid with visually-driven responses (National Academies Press, 2016). This overlap may be why some features of vision, regardless of having improved with time, prevailed under reasonable range seven months after surgery. The clinical indications of the study are two-fold. "Our conclusions show the functional magnetic resonance imaging before the operation as a prognostic instrument for the visual result and pave the way for the advancement of modified recovery programs following visual restoration, Collignon said (National Academies Press, 2016).

References:

Moschos M.M. (2015). Physiology and psychology of vision and its disorders: a review. Medical

        Hypothesis, discovery & innovation ophthalmology journal, 3(3): 83-90.

National Academies of Sciences, Engineering, and Medicine; Health and Medicine Division;

        Board on Population Health and Public Health Practice; Committee on Public Health

        Approaches to Reduce Vision Impairment and Promote Eye Health; Welp A. Woodbury

         Rbb, McCoy MA, et al., editors. Making Eye Health a Population Health Imperative:

         Vision for Tomorrow. Washington (DC): National Academies Press; 2016 Spe 15.3, The

          Impact of Vision Loss.

Respond to Classmate 2 :

Sensory Systems

In this day and age, gene therapy, cell implants, and optogenetics are making strides in clinical attempts of treating various blindness forms (Sokolowski, 2014). When sight is restored to people who have encountered blindness for their entire lives, they would not be in a position to see in the same way as someone who has never lost sight. I think that as much as technology has broken borders and is continually advancing, the rewiring of sensory systems in the blind person's brain might never be complete (Sinha & Held, 2012). The visual cortex maintains a certain degree of plasticity, which is the ability to shift as an experience function. Even after several months from surgery, it would not be entirely possible for the visual cortex to get full normal functioning.

The visual cortex is the brain section that processes eye information. Scientists know that in cases of blindness that is untreatable, the occipital cortex, which is the posterior brain region devoted to vision, becomes responsive to touch and sound to compensate for vision loss (Bottari et al., 2018). This essential reorganization of the brain represents a problem for individuals encountering eye surgery for vision recovery purposes because the reorganized and deprived occipital cortex might be incapable of seeing anymore after being born blind or spending years in the dark (Bottari et al., 2016). The recovery is seen in the visual cortex, which is spotlighted by mitigation in responses that are auditory driven and by a boost in visually driven and grey matter density, is not total after surgery (Mueller et al., 2018). Therefore, I would interpret it as not being a full, healthy recovery. The person would still have some problems when trying to move about since it would be more or less like a new thing to them.

References

Bottari, D., Kekunnaya, R., Hense, M., Troje, N., Sourav, S., & Röder, B. (2018). Motion processing after sight restoration: No competition between visual recovery and auditory compensation. Neuroimage, 167, 284-296. https://doi.org/10.1016/j.neuroimage.2017.11.050 (Links to an external site.)

Bottari, D., Troje, N., Ley, P., Hense, M., Kekunnaya, R., & Röder, B. (2016). Sight restoration after congenital blindness does not reinstate alpha oscillatory activity in humans. Scientific Reports, 6(1). https://doi.org/10.1038/srep24683 (Links to an external site.)

Mueller, I., Poggel, D., Kenkel, S., Kasten, E., & Sabel, B. (2018). Vision restoration therapy after brain damage: Subjective improvements of activities of daily life and their relationship to visual field enlargements. Visual Impairment Research, 5(3), 157-178. https://doi.org/10.1080/1388235039048692 (Links to an external site.)

Sinha, P., & Held, R. (2012). Sight restoration. F1000 Medicine Reports, 4. https://doi.org/10.3410/m4-17 (Links to an external site.)

Sokolowski, B. (2014). Sensory Systems☆. Reference Module In Biomedical Sciences. https://doi.org/10.1016/b978-0-12-801238-3.05298-3