At the University of Oxford, [Jen Chesters] conducts therapy sessions with thirty men in a randomized clinical trial to test the effects of tDCS on subjects who stutter. Men are approximately four times as likely to stutter and the sex variability of the phenomenon is not being tested. In the randomized sessions, the men and [Jen] are unaware if any current is being applied, or a decoy buzzer is used.
Transcranial Direct Current, tDCS, applies a small current to the brain with the intent of exciting or biasing the region below the electrode. A credit-card sized card is used to apply the current. Typically, tDCS ranges from nine to eighteen volts at two milliamps or less. The power passing through a person’s brain is roughly on par with the kind of laser pointer you should not point straight into your eyeball and is considered “safe,” with quotation marks.
A week after the therapy, conversational fluency and the ability to recite written passages shows improvement over the placebo group which does not show improvement. Six weeks after the therapy, there is still measurable improvement in the ability to read written passages, but sadly, conversational gains are lost.
Many people are on the fence about tDCS and we urge our citizen scientists to exercise all the caution you would expect when sending current through the brain. Or, just don’t do that.
Transcranial Direct Current Stimulation – or tDCS – is the technique of applying electrodes to the skull and running a small but perceptible current through them. It’s not much current – usually on the order of 1 or 2 mA, but the effect of either increasing or decreasing neural activity has led to some interesting studies. [Theo] over on Instructables wrote a tutorial for making his own tDCS suppy that will supply 2 mA to electrodes placed on the skull for everyone to experiment with.
The basic idea behind tDCS is to put the positive electrode over the part of the brain to be excited or the negative electrode over the part of the brain to be inhibited. This is a well-studied technique that can be used to improve mathematical ability. It’s not electroshock therapy (although that is a valid treatment for depression and schizophrenia) in that a seizure is induced; tDCS just applies a small current to specific areas of the brain to excite or inhibit function.
[Theo]’s device is a simple circuit made of a transistor, resistors, and a few diodes to provide about 2 mA to a pair of electrical contacts. With this circuit and a few gel electrode pads for your head, you too can experiment with direct current stimulation of your brain.
Of course we need to warn you about putting electricity into your head. In any event, here’s a quadcopter / stun gun mashup we made. Don’t do that, either. You might get a takedown request.