Thursday, January 15, 2015

Some numbers on tDCS research


For medical science to prove that a particular intervention works for a particular condition (depression) or to make a neurophysiological change (improving memory) there has to be numerous studies showing statistical success. It is best when different research methods are used, and repeated over and over again to show consistency. And normally the studies start out small and then larger ones are funded.

For tDCS, the research is very broad, from depression to memory, from pain to Parkinson's; it is so broad it makes me a little skeptical and I wondered how much research has been done on various medical conditions and non medical interventions.

Just recently, in pubmed, I did a simple search of tDCS + (topic) and recorded the number of papers that come up from the search. The results are shown below. I understand that this is only an indication of what is being researched (not all are directly related and all are certainly not positive), but I thought it was interesting nonetheless.

Hits on Pubmed

tDCS and Learning                         322
tDCS and Stroke                             288
tDCS and Memory                          214
tDCS and Depression                     208
tDCS and Pain                                162
tDCS and Safety                             108
tDCS and Cognitive Enhancement  55
tDCS and Bipolar                           31
tDCS and Parkinson's                     25
tDCS and Alzheimer's                    13




Thursday, November 6, 2014

Cognitive enhancement montage location: L A DLPFC, R C Supra orbital



Interest in TDCS for cognitive enhancement and for clinical purposes "at home" is growing due to the broad success in the research, the non invasive nature of the therapy, and the ease of making a device or purchasing a clinical device. Because of the grey area of regulation, the manufacturers of devices that can perform the regulated direct current necessary for tDCS do not shout very loud what to do with their devices. The responsibility where to put the electrodes is generally up to the consumer. Hence this blog entry helps clarify, maybe just a little, how to locate a common montage used for cognitive enhancement (as well as depression): Left Anodal dorsolateral prefrontal cortex (DLPFC) and Right Cathodal supra orbital position.

The L DLPFC and R Supraorbital position is also defined as F3/Fp2 on the 10/20 EEG head mapping system, and on the 10/20 system it looks something like this.




Now if you are looking at this picture, and looking in the mirror it is not exactly clear where these points lie (at least to me)

Even though measuring from cranial landmarks is one way to find these points, I always question measuring on the head, or body, because of the size differences between people. Hence to make it easier to locate the points, below are numerous pictures.

Left Anode Dorsolateral Prefrontal Cortex (DLPFC)
The left is obviously the left side of the head, and the anode is the more positive of the two leads (green wire on the Cognitive kit); current goes from electronics to anode through the head to cathode back to the electronics. For the position of the DLPFC, check out the cranium below:



And on me pointing and with a sponge electrode(see there is an advantage to having little hair, better tDCS montage location and better electrode connection).



Right Cathodal Supraorbital

The more negative electrode goes with the Cathode, often, but not always, the black wire or connector. This position is easier to find. The Supraorbital position is above (superior) to the supraorbital ridge, the brow ridge. Start with your eyes straight forward, move up (superiorly) until just over the supraorbital ridge, there you are. Some pictures below:




Putting it all together:

(for the one above, the L DLPFC electrodes should be under the red band, but there was definitely enough sponge surface area for current flow).

Next will be the primary motor cortex (M1)

Thursday, October 9, 2014

Cognitive kit on its way


The Cognitive kit is a simple to use, safe, very straightforward way to implement tDCS cognitive enhancement sessions. With the Cognitive kit, everything is included to perform safe and easy sessions, with flexibility of any montage. Unlike all other devices, the Cognitive kit includes the more expensive Amrex sponge electrodes in the price of the kit, no expensive adapters, no extras, all included. And it is designed to be small enough to fit in your pocket for more flexibility for the user.

We are a small company, with limited resources so we are growing the company with multiple small builds, each new one larger than the last. Hence it will take a few months to catch up with demand, we apologize.

But this build of the Cognitive kit is on its way (see populated PCBs below). The release date is October 20, but we may be able to release earlier.

See www.cognitivekit.com for more information and email support@cognitivekit.com to find out about early release and release information.


Wednesday, July 23, 2014

The Cognitive kit is available



The Cognitive kit, an easy-to-use hand held cognitive enhancement device, is now available for sale. Cost is $200 and $20 for shipping FEDEX GND US and Canada. We are working on reliable, inexpensive international shipping options but not available now. 

www.cognitivekit.com


Friday, June 13, 2014

Introducing The Cognitive Kit


We are excited to offer a new cognitive enhancement device based on tDCS, The Cognitive Kit. The Cognitive Kit is a simple, safe, easy to use kit that provides everything needed for a safe cognitive enhancement session. Included in the $200 is the hand held device, 2 x 9V devices, headband, and 2 x Amrex sponge electrodes. That's right, we believe in safety and comfort so much we have included the best electrodes in the kit.


The Cognitive Kit will be commercially available in mid July, we are not taking pre-orders (don't believe in them), but if you are interested, after you check out the website, email Keith at support@cognitivekit.com and I will keep you informed of the release.

Sales will be North America and internationally. Shipping charges are still being figured out.


Thursday, May 8, 2014

The Electrical Nature of tDCS


When there is a description of a circuit or circuit elements, you see even some of the smartest people become all glazed over, as if the words current or Ohm's Law inexplicably creates a block in understanding (I must admit, the same thing happens to me with probability math, I just can't get my head around it). The concepts of basic circuit theory are indeed simple, and luckily the circuit theory of basic tDCS is indeed straightforward. I will do my best to dispel some confusion about current flow, brain currents, and anode and cathode.

Consider the drawing below, a simple tDCS setup using current regulating diodes. Firstly, this is a DC circuit, none of the values are changing with time. After it is powered up and reached a steady state, it keeps that value. A current can only occur if there is a closed loop, and since there is only one loop, there can only be one current (I).



In most tDCS circuits a current regulating device is used. That means even with varying input voltage (i.e. as the battery changes) and with varying load (i.e. if the head resistance changes due to drying of the sponges or movement changing the electrode position) the current will still remain the same. Now you see why simple current regulating devices (in this case a Current Regulating Diode (CRD)) are perfectly suited for tDCS. What this means that as long as you have a bias voltage, and an appropriate load, the current will be 1mA, and the current will only flow in one direction.

There is confusion about current direction. We electrical engineers like to use current (because algebraic equations can be used to calculate current and voltage), and in the DC situation, current always flows from positive (+) to negative (-). Not to confuse anybody, but charge (and electrons) flow in the opposite direction but that is not relevant here because all circuit elements are best described using current.

All the math you need for this discussion is Ohms law,  V = I x R or I = V/R. What that means is if there is a smaller resistance, the current will be greater and also if there is a resistance and there is a current, there is a voltage drop over that resistance. OK back to tDCS.

Looking at the tDCS schematic above, the 2k Ohm resistor is there to limit the current; if the CRD fails, and there is 18V at the head. The head resistance will vary due to numerous things, but a good range is 2kOhm to 6kOhm. For worst case, use 2 kOhm. So if there is 18V at the head, and the current regulator is not working, then the maximum current can be 4.5mA (18V/4kOhm).  The 2kOhm will also limit the current in fail mode or normal mode if the electrodes are shorted together. During normal functioning, you can short them together and the CRD is still happy to produce 1mA into a 2kOhm load. This also protects the electronics. Obviously shorting together is not something that happens at the head but when the electrodes are taken off or fall off the head when still on and come together on the table or desk.

With tDCS nomenclature, the current flows through the Anode, the positive electrode, through the head to the Cathode, negative electrode (forget electrochemistry, diodes etc.). I, like many people, have wondered how much current really goes through the brain. Since the dura mater, connective tissue, and the skull will be more resistive than the fluid just under the skin you would think that most of the current travels tangentially under the scalp but obviously some current goes in to the brain. What I have read is that the closer together the electrodes, the more current travels under the scalp (which makes sense).

From a physiological view, it is more complicated. The head is not a true resistor (but for the circuit design, it works to make this assumption), as the skin, connective tissue, skull and then brain have a non uniform electrical characteristic. For the effect on the brain, research scientists are more concerned with current density and achieving the best current density. Hence another reason why the nice uniform current density of the sponge electrode is the best choice. The drawing below shows an imaging of current density with a 2mA DC stimulation. The red is the section where current is flowing into the brain and blue is the section where current is flowing out of the brain.



Lastly you can calculate the current density by dividing the current of stimulation by the area of the electrode, but just knowing that there is a sufficient size electrode, the correct connection between electrode and scalp, and limiting the stimulation level to 2 mA, then the current density is not a concern.








Tuesday, April 15, 2014

TDCS and Cognitive enhancement success, anybody want to do a video for $50?


We are preparing a video and application to run an Indiegogo campaign. The campaign will be based on Cognitive Enhancement, TDCS, and its ability to successfully improve mental performance. The funding will go towards development of Plato, a Cognitive Enhancement device based on TDCS. As part of the development of Plato, we will later be doing a feasibility study on its safety and side effects.But now we concentrate on cognitive enhancement.

Cognitive enhancement is an exciting, and somewhat controversial, method of altering ones mental capacities and changing behavior. Possibilities include improving attention and memory which would benefit the test taker; increased alertness and focus which would benefit those striving for an edge in productivity, and learn a skill faster for example learning a new language for a job. The cognitive enhancement dialogue has resided mostly in the pharmaceutical realm. With TDCS the momentum is shifting and we want to be there.

So for our campaign, in our video, we will be describing the usefulness of TDCS, describing Plato, and we would like to include the videos of people that have had benefit and success in using TDCS in a cognitive enhancement or mood altering method.  And if the video is chosen (3 - 4 will be chosen) we will be giving $50 to the lucky participant.

Please send a video:

  • 20s - 30s long
  • Describing your success in using TDCS in enhancing mental performance, improving insight, memory, altering mood etc.
  • We are more interested in the description of benefits, the story, and less interested in the montage, treatment protocol, etc.
  • The better quality videos as well as better content will be chosen. 3 - 4 videos will be chosen and each will given $50.00.
  • Decision will be made in early May.
So tell us your story, take a video, and make some money!

Email me with questions, and instructions how to send the video, to keith@humanbioelectric.com