Brain stimulation improved visual learning in patients left blind by a stroke or brain injury

A brain stimulation device, which is being developed into a portable version that can be used in homes, boosted visual learning abilities in people left partially blind by a stroke or traumatic brain injury, scientists say. 

Researchers in the US and Italy tested a variety of new brain stimulation techniques to see if any could speed up the painfully slow – and sometimes impossible – process of retraining an injured brain.

The most remarkable effects came from transcranial random noise stimulation (tRNS), which sends low-octane electrical currents to injured parts of the brain, loosening rigid connections to allow more free-flowing thoughts. 

Within 10 days, participants’ scores on tests – connecting the dots and – had doubled. And their progress remained unchanged six months later. 

The findings, published today in the Journal of Neuroscience, form part of a wave of good press for tRNS devices, which have been shown to boost memory in healthy people and to ease depression. 

Transcranial random noise stimulation (tRNS) sends low-octane electrical currents to injured parts of the brain, loosening rigid connections to allow more free-flowing thoughts 

Neurodevices have gained momentum in recent years as a way for both the healthy and the injured to optimize themselves.

The technology is in its early stages, but, predictably, appetite for it is strong. 

For researchers working on traumatic brain injury and stroke, its potential is tantalizing. 

‘The beauty of this combined therapy is the very short training,’ said Lorella Battelli, who lead part of the team at the Italian Institute of Technology and is an assistant professor at Harvard Medical School. 

‘When you work with stroke patients you quickly realize that there is a lot of fluctuation in their ability to stay on task. Thus, training that is short and effective is a big advantage.’

Battelli worked with University of Rochester researchers Duje Tadin, a professor of brain and cognitive sciences, and Krystel Huxlin, MD, a professor of ophthalmology, to analyze various types of brain stimulation techniques. 

First, they gathered a group of healthy people, showing them clouds of dots and asking them which way the dots were moving across a screen. 

This helped the researchers to gauge how well they could perceive and decipher moving objects. 

They then repeated the task, but divided them into groups, with some continuing as before, while others donned one of four brain stimulation devices. 

As expected – as has been demonstrated in previous studies – tRNS boosted memory and learning.

When they were all tested again without the devices six months later, the tRNS group still had elevated scores.

‘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 said.  

Next, they turned to a cohort which hasn’t been studied with these devices: people with brain damage from a stroke or another kind of injury that left them partially blind.

They coupled tRNS with a visual training system developed in Huxlin’s lab.   

The combined method worked: they saw improved scores after 10 days of stimulation.   

‘This fast improvement is something we’ve never seen in this patient population,’ Huxlin said.

The findings are incredibly exciting – though mysterious. 

It worked, but we don’t know why. 

‘It appears that tRNS helps put the brain in a more plastic state, which makes it more amendable to training-induced change, or learning. What we hope to learn with future work is why this happens,’ Tadin said.