Brain reorganizes to compensate for vision loss

When patients with macular degeneration focus on using a different part of their retina to compensate for central vision loss, their brain appears to compensate by reorganizing its neural connections, according to a study by researchers at Georgia Tech’s School of Psychology, Science Daily reported.
According to the article, previous research in this area has shown conflicting results. Some studies suggest that the primary visual cortex reorganizes itself, while other studies suggest this doesn’t occur. Partnering with researchers from the Georgia Tech/Emory Wallace H. Coulter Department of Biomedical Engineering and the Emory Eye Center, Dr. Schumacher and graduate student, Keith Main tested whether the patients’ use of other areas outside their central visual field to compensate for their damaged retinas drives is related to this reorganization in the visual cortex.
Published in the December issue of the journal Restorative Neurology and Neuroscience, the study included 13 volunteers who were presented with a series of tests designed to visually stimulate their peripheral regions and measure brain activity with functional magnetic resonance imaging. When the patients visually stimulated the preferred retinal locations, the researchers found increased brain activity in the same parts of the visual cortex that are normally activated when healthy patients focused on objects in their central visual field. The study authors concluded that the brain had reorganized itself, the report said.
“The parts of the visual cortex that process information from the central visual field in patients with normal vision were reprogrammed to process information from other parts of the eye, parts that macular degeneration patients use instead of their central visual areas,” Science Daily reported.
“Our results show that the patient’s behavior may be critical to get the brain to reorganize in response to disease,” Eric Schumacher, assistant professor in Georgia Tech’s School of Psychology told Science Daily. “It’s not enough to lose input to a brain region for that region to reorganize; the change in the patient’s behavior also matters,” He added.
In this case, that change of behavior comes when patients with macular degeneration make up for their vision loss by focusing with other parts of their visual field, the report said.
According to the article, there is supporting evidence with other tasks that suggests that the brain can reorganize itself. However, this is the first study to directly show that this reorganization in patients with retinal disease is related to patient behavior, the report said.

Source: http://www.sciencedaily.com/releases/2008/11/081120130541.htm
Reported by: EyeWorld News Services