Sep 20 2011

A Bit of Harmless Brain Stimulation

Will classrooms of the future be outfitted with devices that students wear over their heads to stimulate the brain and aid in learning? Well, it’s too early to tell, but a recent study suggests this might be plausible.

Prof Heidi Johansen-Berg and her team at Oxford have been conducting research into the effects of using a small electrical stimulation to the scalp in order to apply a small electrical current – using a transcranial direct current stimulation device (tDCS). (This is different from a transcranial magnetic simulation device, although the principle is the same.) They presented their findings at the British Science Festival in Bradford – I don’t see a published version so I have to go on the press reports.

They had been studying the effects of tDCS on stroke recovery. They found that when applied to the motor areas patients were able to relearn lost motor skill more quickly. They then applied the technique to healthy subjects. They gave them a task to memorize a certain sequence of button presses. They found that the stimulation increased the speed at which they learned the task. However it did not improve the best performance of the subjects.

The researchers speculate that the electrical stimulation may facilitate the changes that occur in neurons in the learning process – increasing dendritic connections, for example. This is an interesting concept. It’s not clear why this would be the case, but it is not implausible.  Perhaps there is also a non-specific effect going on, such as increasing attention.

Before we start applying this technique more research needs to be done. The basic effect itself needs to be confirmed through replication. In addition we need to test the long term effects of tDCS. It has already been demonstrated to be generally safe, but I wonder what the long term effects are on learning.  It’s important to recognize that maximal performance was not improved – so the technique does not seem to make people learn better, just faster. Does the learning, however, have the same staying power, or does it also fade faster? Is the effect sustainable, or does the brain develop tolerance to the effect. And are there other long term effects to using this technique.

As always I fear that with preliminary research into a new device like this one or more companies will decide to market a version of it and make direct clinical claims, before all the follow up research is done. If the idea that electrical stimulation aids learning gets out there, then we can likely expect to see a host of dubious products based upon this claim, many of which probably don’t even function (meaning they don’t produce the same level and precision of stimulation as used in the research).

I also like to think of where such technology can lead. It does seem likely that at some point in the not-so-distant future we will have the knowledge and technology to implant computer devices into brains routinely (we already implant electrodes for stimulation). These could then be used to deliver precise stimulation to networks and structures within the brain to potentially achieve a host of effects, both for disease treatment and general enhancement.

Right now there are three primary ways in which we alter brain function: The first is the traditional method – using the biological sensory inputs and motor feedback, i.e. therapy of one sort or another (traditional learning, talk therapy, physical therapy). The second method is pharmacological – increasing or decreasing the activity of various neurotransmitters.  The third is surgical – removing parts of the brain; for example, removing a seizure focus in order to decrease the frequency of seizures. We are at the dawn of adding a fourth modality – using electrical or magnetic stimulation to directly increase, decrease, or pace the activity of specific areas or networks in the brain.

This fourth modality may prove ultimately to be the most powerful and specific intervention. The brain is, at least partially, an electrical organ and this gives us the opportunity to directly alter brain activity using electrical or magnetic stimulation.

This type of intervention will benefit from advances in a few areas. The first is computer technology, which continues to advance quickly. Smaller, faster, and more energy efficient processors will be helpful – especially energy efficiency, not only because of the need for an energy supply, but also to minimize waste heat.

The second is miniaturized batteries or power cells. Researchers are working on technologies to capture energy from the body and use that to power small implantable devices. This approach is better than a battery.  Current battery technology is still highly limited, and it is not easy to recharge or replace an implanted battery, so any such battery would likely be placed outside the body, which has it’s own limitations. A device that can capture energy from the body, however, would be a continuous source of energy that never needs recharging.

The third area of research is the mapping of the brain itself – getting a more and more detailed map of the modules and networks in the brain and a better understanding of exactly what they do, and the effects of altering their function.

It’s extremely difficult (to the point of folly) to predict future technology. But perhaps we can glimpse broad brushstrokes. If so, I think it’s likely that this type of intervention will increase significantly in the future, and may largely replace pharmacological and surgical interventions.

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