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:
Next will be the primary motor cortex (M1)