Brainwave Entrainment

In the 19th century, it was discovered that the brains of mammals produce electrical activity as part of their normal functioning. This activity was later found to oscillate rhythmically in a measurable (by EEGs), trackable fashion.

Over the successive decades, it was discovered that the whole of a mammal's central nervous system produces oscillations of various sorts, and a method of categorizing and tracking them—based on their frequency, amplitude, and phase—was developed.

Neural oscillations—those that emerge from groups of neurons in the brain—have been some of the most widely studied of these sequences of electrical activity, and this research has led to some practical technologies like pacemakers, and whole new fields of inquiry into how these rhythms might influence the performance of our motor systems and memory, among other aspects of biological operation.