Hemoencephalography (HEG) is a technique based on two main ideas: 

1) That human beings can consciously alter their brain function, changing the signal generated by their brains; and
2) There is a correlation between cerebral blood flow and cerebral neural activation.

HEG offers two approaches, near-infrared and passive infrared, which you can learn more about in the usual place but suffice to say that if you choose the pIR approach you can drastically reduce the complexity of the system and its cost.

A pIR HEG system is essentially an infrared temperature sensor connected to an ADC that reads the temperature and outputs it. A piece of software tracks this measurement and calculates the upward variation rate in temperature. This score can be directly applied to a source of audio/video feedback informing the user of how much blood is flowing in a particular area of the brain. Over time the brain learns that in order to hear the sound or watch the video or make a LED blink faster or brighter it has to increase blood flow.

Despite being relatively simple, a typical commercial HEG system costs several hundreds to thousands of US dollars so its price versus its complexity is shocking to say the least. As mentioned in the previous blog entry, the purpose of this project is to raise awareness to the technique while also democratizing the access to that same technique. With a bill-of-materials between 20 to 40 US dollars I believe it does just that.

And what is this good for? Why bother with any of this? Well, it happens that one of the most suitable areas for using HEG is the forehead. This area is home to the prefrontal cortex (PFC) which is the area that governs the high level executive functions of human beings. Medical conditions like schizophrenia, bipolar disorder, ADHD and major depressive disorder are all associated with a state of decreased cerebral blood flow in the PFC. Then again you don't have to have a medical condition to benefit from this technique, since the PFC is widely believed to play a major role in short-term memory, attention, personality expression, decision making, reasoning among conflicting thoughts and overall cognitive performance, so one could potentially improve all of these by purposely increasing its cerebral blood flow in the PFC region.

So, give it some thought. The worst that can happen to you, I would argue, is a slight headache from consciously focusing too hard on a particular area of your skull as you will not be doing anything that you couldn't already be doing.