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New study shows recovery of vision after stroke

April 10, 2009

A group of neuroscientists at the University of Rochester have shown that intensive training can promote recovery after a stoke.  What’s new is that the patients recovered vision after a stroke had damaged their visual cortex.

A stroke to the visual cortex causes a type of blindness called “cortical blindness” — the eyes still send information to the visual part of the brain but because of the stroke the brain can not process the information and the patient can not see.  Often these strokes affect only a part of the visual cortex leaving the person with a perceptual hole where they have no conscious feeling that they can see.   The traditional view is that there is little recovery after this type of stroke.  But Dr. Huxlin and her colleagues have shown that intensive visual training can promote a remarkable amount of recovery.

The neuroscientists made a simple visual training task and had the patients practice discriminating the direction of movement of a group of dots on a computer screen.  The dots look like snow on a tv, lots of dots moving in lots of directions, but a group of dots move in the same direction, either left or right.

The patients watched the computer screen and had to discriminate if the dots moved to the left or right.  The patients did intensive training, 300 trials a day, with the simple visual motion task.  Then gradually over 20-100 days of training their vision improved.   Surprisingly, the patients became as good as normal subjects at discriminating if the dots moved to the left or right.

I am struck by the tremendous amount of the recovery found in this study.  It is nothing short of amazing and shows how a simple rule — practice, practice, practice — can have a profound benefit.   The potential of the human brain to be retrained by intensive, repetitive, practice is giving new hope to stroke survivors and their families.  I know from watching my father recover from his stroke that daily practice can produce a lot of recovery.  I also know that it is very hard work for the stroke survivor to do these daily training exercises.

This new study provides hope for those with cortical blindness, hope that the right kind of visual training and intensive daily visual exercises can help them to see again.

For  more information about Dr. Huxlin you can look at her webpage.

For more information about this research project you can read the abstract to the research paper by Dr. Huxlin and colleagues published in the April 1st issue of The Journal of Neuroscience.

Perceptual Relearning of Complex Visual Motion after V1 Damage in Humans
Krystel R. Huxlin,1 Tim Martin,1 Kristin Kelly,1 Meghan Riley,1 Deborah I. Friedman,1,2 W. Scott Burgin,2 and Mary Hayhoe3

1University of Rochester Eye Institute and 2Department of Neurology, University of Rochester, Rochester, New York 14642, and 3Department of Psychology, University of Texas at Austin, Austin, Texas 78712-01871
The Journal of Neuroscience, April 1, 2009, 29(13):3981-399

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