Practice results in better learning. Consider learning a musical instrument, for example: the more one practices, the better one will be able to learn to play. The same holds true for cognition and visual perception: with practice, a person can learn to see better—and this is the case for both healthy adults and patients who experience vision loss because of a traumatic brain injury or stroke.
The problem with learning, however, is that it often takes a lot of training. Finding the time can be especially difficult for patients with brain injuries who may, for instance, need to re-train their brains to learn to process visual cues.
But what if this learning process could be accelerated?
That's what University of Rochester researchers Duje Tadin, a professor of brain and cognitive sciences, and Krystel Huxlin, the James V. Aquavella, M.D. Professor in Ophthalmology at the University's Flaum Eye Institute, set out to determine. Motivated by emerging evidence that brain stimulation might aid learning, Tadin and Huxlin collaborated with researchers at the Italian Institute of Technology to study how different types of non-invasive brain stimulation affect visual perceptual learning and retention in both healthy individuals and those with brain damage. Their results, published in a paper in the Journal of Neuroscience, could lead to enhanced learning efficacy for both populations and improved vision recovery for cortically blind patients.
Enhancing learning with brain stimulation
Learning is difficult and often takes a long time, Tadin says, "because after early childhood our brains become less plastic." The brain's ability to change and reorganize itself decreases as a person ages, so learning new tasks, or re-learning tasks after experiencing a brain injury, becomes more challenging.
To test if and how visual perceptual learning might be accelerated, researchers presented study participants with a computer-based task. Participants were shown clouds of dots and were asked to determine which way the dots moved across the computer screen. The task measured the participants' motion integration threshold; motion perception is important in enabling people to see movement and either to avoid or interact with moving objects. Participants 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," Tadin says.
Surprisingly, the researchers also found that when they re-tested the participants six months later, the boosts in performance were still there: the participants in the tRNS group had retained what they had learned and were still able to do better on the motion task compared to the groups that were given other stimulation techniques or training alone.