To put this in real world terms, consider the following: Suppose you are visiting New York and decide to attend a NY Philharmonic (neural ensemble) concert. The higher the amplitudes of the waves, the larger the macroscopic oscillations detected. When enough neurons oscillate together at a given frequency, this gives rise to large-scale, macroscopic oscillations that are significant enough to be detected by an EEG. As you can see, these bands are all very distinct, from the slow roll of the delta wave to the hyperactivity of the gamma wave, and everything in between.Ī neuron may electrically oscillate on and off in a rhythmic pattern, and sometimes multiple neurons in a neural ensemble (neurons that work together on a particular neural computation ) oscillate together in a synchronized way. Scientists have assigned Greek letters to these bands: delta, theta, alpha, beta and gamma. In the figure to the right, you’ll find the five most common EEG bands and their frequency ranges.
Scientists use mathematical models such as Fast Fourier Transforms to extract the band information from the overall EEG waveform. These bands are components of the overall EEG waveform captured at an electrode. In our previous blog, we introduced the idea of EEG frequency bands, which can basically be described as a fixed range of wave frequencies and amplitudes over a time scale.