Have a look at the science behind DARPA research investigating the possibility of enhancing memory using tACS. Dr. Vince Walsh is the lead investigator. Elise Hu and team from NPR reporting.
In a multi-year study at the University of New Mexico, volunteers received a fraction of 9-volt battery’s worth of electrical stimulation to their scalps while they slept at the lab. When they woke up, they were asked to play a video game they had learned the day before. Turns out that subjects were significantly better at it after the night spent in the lab.
Michael Weisend PHD. is a principal investigator at The Mind Research Network, MRN.org, and assistant professor of Translational Neuroscience at the University of New Mexico, Albuquerque. Dr. Weisend and his team pioneered a method for determining optimal brain regions for tDCS stimulation using fMRI. Much of Dr. Weisend’s work is focused on cognitive enhancement in healthy subjects for the purpose of reducing the amount of time it takes to master a skill. He shared a full hour of his time and a wealth of tDCS-related information. Download the interviewhere (zipped mp3). Subscribe in iTunes. (Firefox users- there’s an issue with the html5 audio player. In the meantime you can download the episode or open the page in another browser).
Marom Bikson is CEO of Soterix Medical and Associate Professor at City College of New York in the Department of Biomedical Engineering. Marom is a distinguished tDCS scientist and prominent in the development of HD-tDCS. Download the interviewhere (zipped mp3). (Firefox users- there is an audio player here, but it’s displaying intermittently. Trying to track down the issue. In the meantime you can download the episode or open the page in another browser).
(We got a good forty minutes of interview in before the Skype gremlins caught up with us. I had to cobble an ending together.)
Perhaps depression studies are closest to FDA qualification for tDCS?
(Prediction is very hard, especially about the future – Yogi Berra.)
A device (NorDoc Smartstim) that can go to 4mA is being used in a smoking cessation trial? (Trial info indicates 2mA current dose.)
FDA tDCS approval would be device-specific at first. But would open the door to ‘me too’ mechanism, FDA 510(k)
HD tDCS can have multiple cathodes and or multiple anodes. An array of 4 small anodes splitting 2mA, for example (.5 mA each electrode), can function as an anodal ‘virtual pad’. Assumes cathode somewhere else on the body).
Image By Richard McKinley USAF
Tolerability is how tolerable in terms of side effects a medication is.
A Theory of tDCS (“Gross oversimplification”) As positive current flows into the cortex it passes neurons.
Because of the nature of neurons, this positive current depolarizes somas (cell’s body), increasing excitability, thereby increasing the functionality & plasticity of that region (hypothesis… “We really don’t know.”). Under the cathode, somas (cells) are being hyper-polarized – excitabilty decreases.
A synapse is a structure that permits a neuron (or nerve cell) to pass an electrical or chemical signal to another cell. Pyramidal neuron
Titration, also known as titrimetry, is a common laboratory method of quantitative chemical analysis that is used to determine the unknown concentration of an identified analyte.
TES Transcranial Electric Stimulation
“transcranial electrical stimulation” Merton and Morton 1980
“Priming the network in conjunction with applying tDCS makes a lot of sense, as a way to make the tDCS to do what you want.” (Co-priming – The idea that one would initiate an activity first, and THEN add tDCS.)
I called Weisend recently to see what he thought of people experimenting with tDCS. “In the DIY crowd they don’t have the neuroimaging to start the process and know where to place the electrodes,” he told me. “Their success and their safety are going to be limited.” In the laboratory, subjects go through two or three sessions of tDCS over a week. What happens long term if you do more than that? Nobody knows. And the equipment you order from some random person online may not be as reliable as what’s used in a laboratory.
That said, Weisend believes tDCS can be done safely, and he thinks it might be used to prevent memory loss in the elderly or to help patients recover from traumatic brain injuries. He’s tried tDCS on his own brain hundreds of time and hasn’t suffered any deleterious effects—with the notable exception of a few skin burns that were severe enough to leave scars. “You get attached to your work, I guess,” he says.