Friday, August 28, 2009
Neurosky - EEG for the masses!
The allure of dry sensor technology & a wireless EEG headset had me ordering a Neurosky unit. I was concerned about quality because I wondered how good a unit that costs under $200, whose target audience was gamers would be. The least expensive EEG competitor (assembled) is well over a thousand, and does not use wireless nor the dry sensor technology. This is my review of the unit after having used it for a week. Note that my only other experience is with the Open Source EEG unit, which works quite well, but has to be built, and whose component costs are in excess of $200.
On a visual inspection the unit looks like a set of high quality headphones with an extra arm attached, that might be mistaken for a microphone. The arm contains the sensor that rests against the top of the forehead. It is far lighter that I expected which is a good thing. The headset is adjustable & very comfortable to wear. On the left ear foam there are 3 sensors that are meant to contact the ear, which gives the effective ground. A bluetooth dongle is included. So mechanically, & appearance-wise I was very pleased. Not sure how susceptible this may be to electostatic discharges (I suspect the worse considering the micro-currents being measured), but so far so good...
Neurosky includes 'brain visualizer' software with the unit that is done using a polar coordinate type of display. I was a little offput by this initially and thought about writing an interface for BrainBay, which is an open source application for viewing EEG. Normally I prefer to train in just two bands at a time. But I made an interesting discovery that has me prefering Neuroskys display, and this relates to a fairly serious mistake I made in my training with BrainBay. For several months I trained to reduce delta, and increase the high alpha. In suppressing delta I believe I was also unknowingly suppressing theta, which is the bandwidth directly below alpha. According to some writers, a healthy theta component with the alpha component gives the most effective meditations, and helps in being able to utilize the subconscious to solve problems. The picture at the head of this blog is a capture of the Neurosky BrainVisualizer view showing an unfortunate 'notch' in my theta waves, along with the desired notch in the delta. In posts to come we will see how long it takes me to get rid of this 'notch'.
Using the unit is simplicity itself, and I find myself prefering it over my OpenSource EEG. When you put the unit on & start the software there is a 'signal strength bands' that show whether or not the unit is capturing. Now if I have been outside and am the least bit sweaty, this works great. Normally I have to moisten the areas the 'dry sensors' touch to get a good signal. No doubt this varies from individual to individual. After using it I always clean & dry the sensor areas.
The BrainVisualizer has an interesting delayed time component that allows you to see the change in the polar display over the last few seconds. The old traces fade out, and the new ones show full intensity. This is a really nice touch that gives a quick idea of your trend. There is also a color change that it rotates through that has no purpose other than eye candy (at least as far as I know). This display works very well not only for giving your attention to just a few bands, but the overall picture of brain waves being generated.
There are also meters on the side for 'attention' & 'meditation'. When pegged at 100% they commence doing an interesting flash sequence. I noticed I can get a flashing 'meditation' without any theta component, so I guess the developers did not feel that theta was a necessary component. I wish Neurosky would publish on what they were thinking.
So whats missing? I would like to be able to record and then do averaging on the session. Neurosky provides developer tools for free, so it may be possible to do this addition. I have not tested for calibration but may attempt that in a later post. As a single channel EEG, you will not be able to look for brain synchronicity, other than that it has few limitations & great convenience.
As an EEG unit for under $200, this should make people very happy. I am certainly pleased & plan on purchasing some additional ones as gifts.