Blindness Article Questions

1. What major recent shift in our understanding of the brain is described at the beginning of the article? What may be the practical importance of this shift?
      Neuroscientists now understand that the brain is capable of significant change and adaptation. The importance of these findings deals with the understanding of how sensory input in patients who are blind has changed or adapted so that advancements can be made in the field of sensory substitution and restoration devices.

2. How are blind people able to cope with their environment? Might their other perceptual abilities be unusually good? Might blindness lead to disruptions of development that impair other perceptual abilities? What does the evidence show on these questions?
       Blind individuals have to make major adjustments in order to interact effectively with their environment. Despite the common belief that individuals who lack sensory function in one of their senses develop superior abilities in their other senses, in fact blindness has the potential to disrupt brain development and knowledge acquisition. It has been studied and found that blindness has detrimental repercussions on the processing of spatial information that is gathered through the remaining senses.

3. How do blind people read? In what other ways does their communication compensate for absence of vision? What part of the brain may allow these adaptations to blindness?
        Blind people read Braille, using the pad of their fingers to touch an array of raised dots. This scanning of spatial information with their sense of touch, interprets the dots into meaningful patterns that translate to semantic and lexical properties. A blind patient also relies on verbal descriptions and verbal memory in place of visual perception. The visual cortex, which is used by a sighted person to recognize objects and read visually, does the same job in blind person who reads by touch and relies on verbal language.

4. What does brain imaging (fMRI, PET) evidence show about what part of the brain may be involved in reading Braille, at least in people who lost their vision early in life? Is the same activation present for other tasks involving touch? Does a similar reorganization occur in other forms of sensory loss?
        Evidence shows that the both sides of the visual cortex, in the occipital lobe, was activated while early-blind subjects read Braille. The same evidence was reported in the primary visual cortex when early-blind subjects performed tactile-discrimination tasks such as angle discrimination, but the same activation did not occur when the same subjects tried to feel a homogeneous pattern of Braille dots. Cross-modal plasticity has also been reported in the auditory domain, so basically it works generally the same way with other senses too, but in their general areas.

5. Does the occipital lobe play a casual role in adaptations to blindness? What observations were made in a stroke patient?
       Functional neuroimaging has established an association between activity in the brain and performance, rather than a casual link. To establish a casual link, scientists studied patients with localized brain damage. Because evidence shows that patients who were able to proficiently read Braille became unable to do so following a bilateral occipital stroke, the notion of a casual link is supported between the ability to read Braille and the occipital function.

6. What is TMS? What effect does it have when applied to the somatosensory cortex of sighted and blind people? What effect does it have when applied to the occipital cortex? What do these results imply?
      TMS is transcranial magnetic stimulation. It disrupts cortical activity and creates a "virtual lesion." It impaired the ability of subjects to identify Braille letter but not embossed Roman Letters, when applied to the occipital cortex. In sighted and blind subjects who had TMS delivered to the somatosensory cortex, it interfered with detection of tactile stimulus presented 20-40 milliseconds earlier. The evidence showed that tactile information reaches the cortex by the somatosensory cortex, which is engaged in detection , while the occipital cortex contributes to the perception of tactile stimuli.

7. What happens to the occipital cortex of people who are blindfolded for several days? Is this the same change as is observed in blind people?
       The primary visual cortex is recruited in blindfolded subjects to process tactile and auditory stimuli. Due to the speed of the functional changes it can be concluded that no new cortical connections are established, only previous connections are used. These findings differ from those of early-blind subjects who have more activity in the occipital cortex from tactile domain.

8. What differences have been found between those who lose their vision early (before 4-6 years of age) and those who lose it late in life? What is the role of the occipital cortex in verbally memory in blind people?
       Using a verb-generating test, it was found that early-blind patients differ from late-blind patients in parts of the brain that were used in creating verbal responses. Although the occipital cortex was active in both groups, it was substantially more so in early-blind subjects, especially in the left hemisphere, as opposed to the sighted control group that showed activation in the typical language related areas (Broca's area).

9. What two major processes may account for the adaptations of blind people? Might the occipital cortex have broader roles in everyone? What important practical implications may arise from work like that discussed in this article?
        The brains ability to reorganize  the occipital lobe from processing visual information to processing the information of other senses, and the occipital cortex's possession of the computational machinery necessary for the processing of non-visual information accounts for the possibility of adaptations of the brain in blind people. Because of the occipital cortex's ability to be the ideal processor of visual information in sighted patients and it's ability to structurally change by establishing new neural connections in blindfolded and blind patients, does give it a fundamental role in the processing of sensory information. The occipital cortex's plasticity imply that there is a good chance of not only the brains adaptivity for survival but the potential for individuals to compensate for their disabilities and technological aid in repairing or substituting for a person's ability in sensory processing.