Blind World Magazine


Macular Degeneration.
Study shows brain reorganization occurs in sufferers of macular degeneration.





February 19, 2005.
Law & Health Weekly.




The McGovern Institute for Brain Research at MIT announced that Postdoctoral Associate Chris Baker and Principal Investigator Nancy Kanwisher in collaboration with Professor Eli Peli from Harvard Medical School have discovered the first evidence that brain reorganization occurs in people suffering from the progressive visual disorder macular degeneration.


Baker, Peli and Kanwisher's study, titled "Reorganization of Visual Processing in Macular Degeneration," is published in The Journal of Neuroscience.


Macular degeneration is the leading cause of blindness in the developed world, affecting over 1.7 million people in the United States, and tens of millions worldwide. In macular degeneration, the center of the retina is damaged and sight is limited to peripheral vision. People suffering from this disease have blurry vision, often causing severe difficulties with everyday tasks such as reading, driving and recognizing people.


"Our major finding is that the part of the brain that processes only central retinal visual information in people with normal sight reorganizes itself in people with macular degeneration to help process peripheral visual information," said Baker.


The McGovern Institute study was conducted by Baker and Kanwisher in collaboration with Peli at the Schepens Eye Research Institute, Harvard Medical School. Using advanced brain imaging techniques and state of the art retinal mapping techniques, the researchers monitored which parts of the brain process visual signals in people with macular degeneration compared to people with normal vision.


"While our findings do not have immediate clinical application, the fact that a larger region of the cortex is recruited for peripheral vision in people with macular degeneration is encouraging, and suggests that it may be possible to develop new rehabilitation strategies that exploit this increased cortical involvement to partially compensate for loss of retinal function," said Kanwisher.


Highlights include:


-The part of the brain dedicated to processing central visual information can reorganize itself in people with adult onset macular degeneration to process peripheral visual information;


-People with normal vision cannot use this brain area to process peripheral vision information.


-Researchers used a brain imaging method known as "functional


-MRI" which reveals the parts of the brain that are active when subjects perform perceptual and cognitive tasks. Brain imaging was conducted at the Martinos Center for Biomedical Imaging.


-Functional MRI tracks the changes in blood flow to each region of the brain.


Baker, Peli and Kanwisher plan to explore whether this newly-discovered brain reorganization enables people with macular degeneration to see better with peripheral vision than normally-sighted people, and to identify the conditions that lead to these changes in the brain (i.e. when and how quickly after the onset of macular degeneration does reorganization occur).


Answers to these questions will lead to a better understanding of how modifiable the human brain is, giving further insight into the consequences of the disease and the prospects for rehabilitation.


How the brain develops and is organized are among the oldest questions in neuroscience, and The McGovern Institute's researchers are undertaking research, which seeks a new understanding of routine brain functions such as recognition, perception and decision-making.


The McGovern Institute for Brain Research at MIT is a research and teaching institute committed to advancing understanding of the human mind and communications.




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