Hearing the Signal

The skull is a very poor conductor of electricity; it tends to “smoosh” (to use a technical term) the EEG from a fairly broad area–about 10 square centimeters of brain surface.  That’s one reason why it’s not absolutely critical to be in an exact site to train a specific area of the brain.

Also, neurons tend to work in pools (like synchronized swimmers), so we aren’t really looking at the summed results of a bunch of individual neurons but of much larger batches working together. That’s why coherence is so much stronger between two sites the closer together they are. And that’s why the likelihood of training a monopolar montage is not terribly likely to increase coherence or reduce phase angle at one site–because they are already pretty high.

An individual neuron (or neuron pool) firing doesn’t produce an amplitude (since amplitude is measured in microvolts, and voltage is a measure of the difference in electrical force between two sites), and it doesn’t produce phase (since phase is a relationship between two lines with peaks and troughs.)  An individual neuron/pool just does what it does, and we apply these various measures to it in comparison with some other site.

Neurons generally have a recharge period between firings, they don’t fire consistently as fast as they can, so although a pulse may be quite short, the number of pulses per second are not in the range of hundreds of Hz.