More On BioFeedback 2
Magnetic Stimulation
My experiments with Shakti led me to try out the Shakti coils for some experimentation with regular magnetic entrainment. Depending on what you're doing, you could call it TMS, or trans-cranial magnetic stimulation.
As it turns out, the Shakti coils are actually inexpensive telephone pickup coils (click on photo for link):
One tricky thing about the coils is that if you are using more than one, you want to use pairs with alternating polarity, as it seems to help out with the magnetic field (basically forming complementary fields, circles of electromagnetism as it were). So if you were using a pair like the one in the picture, you would have one with the suction cup up, the other would have the suction cup down. Except that you'd probably remove the suction cup. The ones supplied with Shakti attach with velcro. I plugged the coils into the output of an mp3 player that was playing a 10hz wav file created in CoolEdit. Note that not all players may be able to output a signal this low. If not you might be able to use a higher frequency to modulate the lower one and sneak it through that way.
Magnetic stimulation is by far the most powerful form of entrainment I have encountered, and I would be cautionary about its use. I found that sometimes it was as if the entrainment just wouldn't "catch," and no entrainment would occur, but then sometimes it would - with extreme effects. The nice thing about magnetism is that it won't effect the EEG, so you can monitor what's going on. First time I did it I saw my 30 second average alpha amplitude soar to 100uv, which let's just say is a lot. Gave me a bit of a foggy head for a few hours.
I wouldn't be comfortable using this without constantly monitoring EEG. Also, I used a Gauss Master (aka Dr. Gauss) to measure the output at about 10 milligauss, same as Shakti.
NeuroTrek CES
CES is Cranial Electrotherapy Stimulation. An electrode that is covered with saline soaked felt is placed on each earlobe and a pulsating current is passed through the circuit. Typical recommended settings would be something like a 0.5hz pulse modulated by something like a 100hz wave, with a 50% duty cycle. Neurotrek and some other units can also be used as TENS units for pain.
The CES market seems to be dominated by Alpha-Stim, with a lot of research (largely done by Alpha-Stim/Kirsch) recommending its use for treating anxiety, depression, and insomnia. As I suffer to some degree from this whole triad, I was fairly interested in CES. I was lucky enough to have a friend lend me a NeuroTrek to try out.
The Alpha-Stim is a one-size-fits all device, although the most expensive model does have 3 frequency settings. But unlike the Alpha-Stim, the NeuroTrek unit is a CES device with all the settings user configurable, so you can experiment with the basic frequency, the modulation frequency, and the duty cycle. And like all CES units, you can adjust the intensity (amplitude). So that's a pretty cool idea for a device.
Although I have had some very subtle effects, I have not found any significant subjective entrainment with the unit, at any frequency or setting. You can't objectively measure it with an EEG because its own electrical signal contaminates the EEG. And because of the electricity involved, you can feel it "working," which to me means CES may have a stronger placebo effect than many devices.
I have found some significant decreases in theta, alpha and beta amplitudes when doing EEG training immediately following a CES session. But no real effects for me regarding sleep, which is what I was mainly interested in.
EEG Tips and Tricks
Finding 10-20 sites on the head: When I first got into it, I spent a good half a day measuring my head and trying to come up with ways of locating the various sites. At first I found it useful to take a key distance such as nasion to Pz, and have a strip of canvas cut to that measure. And that kind of thing is probably necessary when starting out, but I'm not sure that extreme accuracy is ultimately either necessary or useful. My assumption here is that small variations in placement may actually be helpful, as it should encourage the brain to generalize the learning over a larger area.
At any rate, there are a number of landmarks that can be useful in finding sites. The "Z" line, the midline of the head is easily found. The Centrals are found on a line coming straight up from the front of the earhole. The Occipitals are found along the "bump" on the back of the head. The Parietals can be interpolated as midway between the Centrals and Occipitals, and the Frontals can be extrapolated by taking the Parietal-Central distance and going forward from the Central line. The line containing the Temporal sites as well as F7/F8 can be thought of as a couple of finger widths above the ear. Similarly the Fp sites above the brow, which I think of as basically above each eye. I think of O1/O2 as not only being on the "bump," but as eye-width apart as well, kind of straight back from the eyes.
Why this kind of information is not in the basic neurofeedback books is beyond me.
Pendant remote "on": I don't know how this works with other units and software, but with Pendant EEG/BioExplorer you can set everything up, then turn the Pendant off, press play on BioExplorer, then you can get in position, get settled, and only then turn the Pendant back on. The BioExplorer session will not start until the Pendant is actually on. I have found this very helpful when doing deep states training, as it allows one to get comfortable in a reclining position before starting a session. It also allows you to remotely pause BioExplorer by turning the Pendant off, although if you have anything set to play without feedback, these will play.
Alcohol Prep Swabs: Although I don't use NuPrep for abrading the skin, I do find that scrubbing the surface with alcohol helps me get consistently good connections. When I first got started I wrote off the use of alcohol as something that was needed in multiple client situations to keep the equipment sanitary, but as it turns out it definitely helps with the connections. Maybe it helps dissolve the oils from the skin. I make sure I really scrub the areas hard, so I'm getting a little bit of abrasiveness as well. You can get boxes of these individually packaged, very handy.
BioExplorer Data Dumper: For getting the most accurate data out of BioExplorer, the BioExplorer Data Dumper.
19 site EEG combinations: Let's say that within the 19 site 10/20 locations you wanted to train every possible 2-site combination, and you wanted, as much as possible, to train different sites each time, and to go as long as possible before hitting one of the same sites. Here is one such way to do it, developed with Excel using a few rules and a genetic algorithm add-in. There are 171 combinations.
Probably an ideal place to do meditation on the breath, because your breath is quite loud while using earplugs and in combination with the small, hard surfaced space of the tank. They supplied large silicone earplugs that covered the entire earhole from the outside, which worked quite well to seal out the epsom salt (1000 lbs.) soaked water.
Very quiet, very dark, very floaty, and deeply relaxing. Very little sensory input, although occasionally you will brush up against the sides. When I first got in, I felt disoriented, with a sense of motion as if I was floating all around, but this soon went away. The default float position, with hands at the sides, sometimes left my neck in a mildly uncomfortable position, as your chest floats relatively high and your head relatively low, so your neck is craning back a bit more than is ideal, at least for me. I experimented with hands in a relaxed "hold up" position with the hands up but elbows down, as well as hands on chest, which remedied the neck back position but ultimately these were not as relaxing.
Very relaxing of course, an interesting experience, but I doubt I'd do it again. For me, a reclining meditation is equal to this, if not better.
When using the "ping pong" setting on the L&S machine, which alternates the light pulses from left to right, the entrainment effect is very strong, BUT you get entrainment at all the harmonics as well. So if you've set the machine at 10hz, you're getting 10hz, 20hz, 30hz, 40hz, and that's as high as I can measure (see example at the right, which shows EEG amplitudes with the "ping pong" entrainment). Which is not what I'm looking for, but your mileage may vary.
Reclining chair: And for doing deep states training, I have found the so called zero gravity chair to be quite good as an inexpensive recliner. That is, if you're not prone to falling asleep. This chair can currently be had for about $85 shipped to your door.
BioExplorer BxAdaptor: This is used to control the brightness (and depending on the source, the volume) of your computer monitor. BioExplorer can do this with DVDs, but this little addon will do it with your computer itself, you just need to add a Server object to your design. For eyes open training I use this to surf the web as visual feedback, and I usually have standard audio feedback going on at the same time. It's free, and is available in the files section of the Yahoo BioExplorer group.
The Float Tank
I suppose this is the stuff of legends, with John Lilly's journeys, etc. A sensory deprivation tank is something I always wanted to try, and finally there was one in my town. There are at least a couple of directories of float tanks on the web (floatation.com and floatforhealth.net).
Entrainment
Entrainment is the principle of providing some kind of audio, visual, electrical or magnetic stimulus in the frequency of certain brainwaves with the goal of getting the brain to increase the amplitude of the waves at that frequency.
I have certainly subjectively felt some entrainment from audio (binaural beats or pulses) but as of yet I haven't spent any time measuring it with EEG. But I have spent some time measuring the entrainment or lack thereof from the light portion of light and sound machines. I find very little, if any entrainment occurs when left and right are flashing in sync, but at least with that approach the entrainment seems to be targeted at the right frequency.