Brains are very malleable. The ability of neurons to develop new connections in the brain and to strengthen or weaken existing ones is how we are able to get better with practice – from playing the piano to juggling to learning a foreign language.
- Transcranial direct current stimulation has been shown to improve learning, though it's not entirely clear how it works. Photo: Rheingold
This leads to the inevitable question: is there a way to manipulate our brains to speed up learning?
A previous study from 1999 showed that London cabbies, who have to take “The Knowledge” test to show they are intimately familiar with all the main London routes, have an enlarged hippocampus – the brain region crucial for recalling spatial representations. The more experienced the cabbies, the larger their hippocampus, indicating that as they had got better at memorising and recalling the streets of London, so their hippocampi had grown. It gets easier to perform well-practised tasks like this because the brain gets more efficient at it.
Now, scientists are using this knowledge to work backwards and improve learning – branching out of the clinical world of brain-damaged patients and into the futuristic world of zapping your own brain.
Rehabilitation following stroke is a huge research area. Stroke can affect the speech and mobility of a patient, and treatment often involves re-learning simple tasks needed for everyday life as the brain tissue that underlies these skills has been damaged.
Dr Heidi Johansen-Berg and her team at the University of Oxford specialise in monitoring neurorehabilitation, the process in which damages to the nervous system are healed. They aim to find clues to how brain connectivity and plasticity, essential to learning, works.
Showcasing their work at the British Science Festival this month, they described their explorations of the possibility of using non-invasive electrical stimulation to speed up the relearning of skills in stroke patients. By placing electrodes on the scalp, they could induce a current through the brain to improve the efficiency of the learning process.
- Modelling a tDCS unit, with electrodes at the front and back of the head
Neural impulses are transmitted from one brain cell to the next when fluctuations in the electric potential of the cell membrane – the cell’s voltage – get large enough to surpass a threshold. When this happens, the resulting action potential is large enough to jump the gap to the next neuron, by putting into motion a series of chemical processes that excite the second brain cell.
The team’s idea was that adding more electricity to a brain region would result in more action potentials being generated. Neuroplasticity responds to the frequency and intensity of such synaptic transmissions, so the brain would be able to repair itself much more quickly.
The idea worked. Transcranial direct current stimulation (tDCS), as the technique is known, was successful in improving the recovery of motor skills, although it’s not yet clear how it achieves this.
What the researchers also discovered, quite unexpectedly, was that it had a similar effect on healthy controls – their speed of learning was increased, too.
Touch the tip of your thumb and your forefinger together. Then touch your thumb and second finger together, and continue doing this with all your fingers. How quickly can you do it? Now try doing it with both hands, in opposite directions – so you start with your left forefinger and your right pinky. How long would it take you to do it perfectly at high speed? The answer is much quicker if you electrically stimulated your brain.
So what of learning?
Johansen-Berg is turning her attention to exploring the potential for tDCS with long-term use, as most studies have only investigated effects over minutes or hours. Other researchers, including Allan Snyder, director of the Centre for the Mind at the University of Sydney, are looking at how the technique can aid problem-solving (i.e. making you more intelligent) and is hoping to develop a “thinking cap” to optimise brain function for a particular outcome.
It’s a far cry from the likes of The Matrix or this year’s Limitless, but at only a few hundred pounds for the tDCS technology, it’s not unreasonable to see everyday applications becoming a reality.
Emma Roscow
