Innovation

Electric Currents To The Brain's Visual Cortex Can Temporarily Improve Vision

If we have trouble focusing on an object, we're likely to reach for our glasses or put on our contacts to see clearer. However, scientists at Vanderbilt University believe vision correction could be as simple as zapping the brain. According to a recent study published in the journal Current Biology, mild electric currents used to stimulate the brain's visual cortex may temporarily lead to sharper vision, and affect visual processing and our overall sense of sight.

Stimulating the brain with electric currents has been shown to help with everything from preventing migraine attacks to helping us learn from our mistakes. Now, researchers at Vanderbilt University believe Transcranial Direct Current Stimulation, or tDCS technology, could enhance the way we process visual information.

"This kind of stimulation can improve cognitive processing in other brain areas, so if we stimulate the visual system, could we improve processing? Could we make someone's vision better — not at the level of the eye, like Lasik (laser treatment) or glasses, but directly at the level of the brain?" said Geoff Woodman, co-author and associate professor of psychology at Vanderbilt University, in a statement.

The answer, it turns out, is yes, though they’re still not exactly clear how electric current improves vision. They believe the electricity could boost visual signals in the brain so that certain neurons can process them more quickly. They also theorize the current creates a white noise effect, where irrelevant information is not processed, and therefore, the brain absorbs the actual subject matter more easily.

In the study, a total of 20 young, healthy people who had normal or near-normal vision were asked to evaluate the relative position of two identical vertical lines and determine whether they were perfectly aligned or offset. This test is more sensitive than a standard eye chart — with big letters up the top, getting smaller as they progress to the bottom — because it allowed for more precise assessments of the participants' vision.

The researchers delivered a very mild electric current to the visual cortex located at the back of the brain. After 20 minutes, the participants took the visual line test again, with 75 percent showing measurable improvement for as long as two hours. Several variations of the experiment were performed to test the effects of different intensity levels, current directions, and electrode placements.

Eyes New research suggests Transcranial Direct Current Stimulation could enhance the way we process visual information. Pexels, Public Domain

In the next experiment, the researchers changed the position of the electrodes, applying the current elsewhere in the brain, and not directly to the visual processing center. The findings revealed the participants' eyesight did not improve, suggesting the vision benefits of stimulation are limited to the visual cortex.

Finally, the researchers had the participants read a standard eye chart before and after having a current applied to their visual cortex in order to test what improvement the current stimulation might give people in a more real-world scenario. After stimulation, on average, the participants were able to identify one or two small letters that they weren't able to identify before.

"We saw that those who came in with poorer vision, who might be on their way to needing glasses, had these big leaps, while others who came in with excellent vision showed no change," said Robert Reinhart, lead author and an incoming assistant professor in the department of psychological and brain sciences at Boston University, who conducted this research as a Ph.D. student, in a statement.

Although this effect was observed only in a small sample size, it makes sense that sending electric currents to the visual cortex could offer benefits in visual processing. Previous research has found evidence that electrically stimulating other parts of the brain can boost our cognitive processes, such as improving memory. Researchers zapped the brain of laboratory mice with electrical stimulation to boost both their memory and mental performance. They found that an increased production of BDNF (brain-derived neurotrophic factor), a protein essential to brain growth, was responsible for the surge in memory and plasticity. The protein is synthesized naturally by neurons and is important for neuronal development and specialization.

tDCS could potentially help researchers further probe the basics of human vision and how the brain processes visual stimuli.

"Now we have a new tool that could be valuable for researchers investigating fundamental questions about how the visual system works," said Reinhart.

Eyeglasses and contacts could soon be a thing of the past, when 20/20 vision becomes as simple as a brain zap.

Source: Reinhart RMG, Xiao W, McClenahan LJ et al. Electrical Stimulation of Visual Cortex Can Immediately Improve Spatial Vision. Current Biology. 2016.

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