Brain Training Helps Stroke Victims See Again

§ April 1st, 2009 § Filed under brain research, neuroscience, plasticity § No Comments

Stroke Victim Retrains Sight

Stroke Victim Retrains Sight

A study by Scientists at the University of Rochester Eye Institute has shown that patients can recover sight loss caused by a stroke. The patients engaged in intensive prolonged visual brain training, stimulating neuroplastic change.

“We were very surprised when we saw the results from our first patients,” said Krystel Huxlin, Ph.D., the neuroscientist and associate professor who led the study of seven patients. “This is a type of brain damage that clinicians and scientists have long believed you simply can’t recover from. It’s devastating, and patients are usually sent home to somehow deal with it the best they can.”

A stroke affects the brain not the eyes, visual information still reaches the brain but the brain cannot construct images from it. The team used this “blindsight” – unprocessed visual information that still reaches the brain.

“The question is whether we can we recruit other, healthy regions of the brain to benefit the person’s vision. Can we train those brain regions so hard and stimulate the brain to such a degree that this visual information is brought to consciousness, so the person is aware of what they’re seeing?” said Huxlin.

The four women and three men in the study in their 30s through their 80s had suffered substantial damage to the primary visual cortex.

The team focused on motion perception, critical for most everyday tasks, aiming to see whether they could stimulate the brain’s middle temporal region, healthy in the participants,  to take on some of the tasks normally handled by the visual cortex.

The five participants who performed the training and completed the experiment had significantly improved vision. They were able to see in ways they weren’t able to before the experiment began. A few found the experiment life-changing – a couple of participants are driving again, for instance, or have gained the confidence to go shopping and exercise frequently.

Following the dancing dots that can’t be “seen”

Participants fix their gaze on a small black square in the middle of a computer screen.

Every few seconds, a group of about 100 small dots appears within a circle on the screen, somewhere in the person’s damaged visual field – when the patients stare at the square, they don’t initially see the dots. The dots twinkle into existence, appear to move as a group either to the left or the right, then disappear after about one-half second. Then the patient has to choose whether the dots are moving left or right. A chime indicates whether he or she chose correctly, providing feedback that lets the brain know whether it made the right choice and speeding up learning.

But how do patients choose if they can’t consciously see the dots?

“The patients can’t see the dots, but they’re aware that there is something happening that they can’t quite see. They might say, ‘I know that there’s something there, but I can’t make any sense of it,’” said Huxlin, who is also a faculty member in the departments of Ophthalmology, Neurobiology and Anatomy, Brain and Cognitive Sciences, and in the Center for Visual Science.

But the brain is able to make some sense of it all, even though the patient is unaware that he or she is seeing anything. When forced to make a choice, patients typically start out with a success rate of around 50 percent by guessing. Over a period of days, weeks or months, that number goes to 80 or 90 percent, as the brain learns to “see” a new area, and the visual information moves from blindsight to consciousness. Patients eventually become aware of the dots and their movement.

As patients improve, researchers move the dots further and further into what was the patient’s blind area, as a way to challenge the brain, to coax it to see a new area.

“Basically, it’s exercising the visual part of the brain every day,” said Huxlin. “It’s very hard work, very grueling. By forcing patients to choose, you’re helping the brain re-develop.”

The patients in the study did about 300 tests at a time, which translated roughly to sitting in front of a computer for 15 to 30 minutes once or twice a day, every day, for nine to 18 months. It’s an exhausting task, especially for someone whose brain is working extra-hard to accomplish it.

Working with Huxlin on the work were Tim Martin, Ph.D., post-doctoral research associate; Kristin Kelly, formerly a technical associate and now a medical student; former graduate student Meghan Riley; neuro-ophthalmologist Deborah Friedman, M.D.; neurologist W. Scott Burgin, M.D.; and Mary Hayhoe, Ph.D., formerly of the Department of Brain and Cognitive Sciences at the University of Rochester, and now at the University of Texas at Austin. The University of Rochester has filed a patent on the technology.

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