Recently, I had the opportunity to attend a tES (transcranial electrostimulation – a term covering both AC and DC stimulation) and TMS (transcranial magnetic stimulation) workshop at University College London’s neurology department, hosted by Rogue Resolutions. This short video includes a clip of me delivering TMS to a fellow workshop attendee.
It was great to get some actual hands-on experience with these technologies. Although the workshop was primarily aimed at post-doctorates and PhDs, no one bothered to check my credentials, and of course once I was there and had a chance to speak to everyone it was obvious that I was rather more clued in than your typical person off the street.
Medical tES boxes are large and heavy, and nothing like the consumer stimulation devices you can buy online or manufacture out of parts from RS. The doctor in the video demonstrating how to set up the tES machine says she is the only NHS medical professional in the UK who uses tDCS to treat depression.
The trickiest thing with the TMS is getting the coil lined up at both the right location and angle. A camera mounted on a tall frame locates where the coil is in space by spotting the assembly with the three white globes mounted on top of the coil, and transmits this information to a computer so you can see on the screen where to position the coil. The system they are using to do this is called Brainsight.
In this demonstration, the volunteer has electromyograph (activity from the muscles) electrodes on her right hand. The TMS is stimulating the part of the motor strip that activates the relevant part of the hand. Once I had found the exact right location with the TMS coil, you could see the increase in EMG activity. The TMS machine was set up to deliver one magnetic burst per second automatically; I didn’t have to press anything. One burst of magnetic stimulation activates the cortical neurons to fire. This differs from those somewhat dramatic looking demonstrations you might have seen where a train of stimulation is delivered that, for example, interrupts the volunteer’s speech. That is a different use of the technology that creates “virtual lesions”.
One intriguing thing for me as a person interested in EEG research was the demonstration of the use of first tACS and then tDCS on one of the staff while taking an EEG recording at the same time. I had previously been advised that such a thing was impossible, since EEG picks up the miniscule changes in electrical activity from the brain through the skull, and adding an external source of electrical stimulation would naturally introduce a lot of “artefact” (noise in the signal) or render the recording unreadable. Apparently, electronics technology is now so advanced that there are EEG systems that are designed to be used during electrical stimulation of the brain. Naturally, these systems cost a LOT of money!
It was great to actually meet people who are doing research in the field, and to listen to lectures discussing the most up-to-date brain stimulation research.
SevenSigma Project 