Brainwaves represent the electrical activity of the 100 billion neurons within the brain, each one communicating with its neighbors via chemical neuro-transmitters that bridge the synapses between neurons. On average, each neuron has 5,000 synaptic connections. While the electrical activity of a single neuron is too minuscule to measure, the combined activity of all these neighboring neurons is easily detected by modern electroencephalographs (EEGs), though it is worth noting that EEGs struggle to identify activities that lie deep within the brain, far below the scalp to which the machine’s sensors are attached.
This electrical activity demonstrates wave-like patterns that can be separated into distinct frequencies, graded according to the number of waves per unit of time. The first brainwave to be identified in this way was, not surprisingly, the Alpha wave, in 1908. Since then, several other distinct wave forms have been described, and each one corresponds to a different state of consciousness. Normally, the human brain will exhibit a combination of several frequencies at any one time, but one of those frequencies will tend to dominate, depending on whether the person is awake, asleep, or somewhere in between. As we shall see, it is this close connection between brainwave activity and states of mind that enables us to deliberately control our minds by harnessing brainwaves that correspond to the desired state.