Brain stimulation helps patients relearn sight

A new study shows brain stimulation can enhance a patient's ability to retrain their brains to process visual information after a stroke or an injury.


Practice results in better learning and the same holds true for cognition and visual perception: with practice, a person can learn to see better, but the learning can be slow. University of Rochester professor of brain and cognitive studies, Duje Tadin and ophthalmology professor Krystel Huxlin, set out to determine if this process could be accelerated.


Collaborating with researchers at the Italian Institute of Technology they studied how different types of non-invasive brain stimulation affected visual perceptual learning and retention in both healthy individuals and those with brain damage. In a paper in the Journal of Neuroscience, they say their results could lead to enhanced learning efficacy for both populations and improved vision recovery for cortically blind patients.


“Because after early childhood our brains become less plastic,” learning is difficult and often takes a long time, Prof Tadin said. To test if and how visual perceptual learning might be accelerated, participants were shown clouds of dots and asked which way the dots moved across the computer screen. They were then asked to perform the task while sub-groups were given different types of brain stimulation, each involving a non-invasive electrical current applied over the visual cortex. The researchers found that one particular type of brain stimulation, called transcranial random noise stimulation (tRNS), had remarkable effects on improving participants’ motion integration thresholds when they performed the task.


“All groups of participants got better at the dot motion task with practice, but the group that also trained with tRNS improved twice as much and was able to learn the motion task better than other groups,” Prof Tadin said. When they re-tested the participants six months later, the boosts in performance were still there.


Prof Huxlin had previously developed an eye-training system to assist stroke patients with recovering vision, teaching undamaged areas to process visual information that would normally be processed by the damaged parts.


Working with participants who had experienced traumatic brain injuries, the researchers applied Prof Huxlin’s visual training therapy and the tRNS brain stimulation to both damaged and undamaged parts of the patients’ brains. These participants, too, experienced improvement in visual processing and function after only 10 days.


“This fast improvement is something we’ve never seen in this patient population,” Prof Huxlin said. Collaborator A/Prof Lorella Battelli agreed, “The beauty of this combined therapy is the very short training. When you work with stroke patients you quickly realise there is a lot of fluctuation in their ability to stay on task. Training that is short and effective is a big advantage.”

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