Figure 1 from: Johannisson T (2020) Variation in length of alpha waves reveals how forebrain activity is organized. Research Ideas and Outcomes 6: e49942. https://doi.org/10.3897/rio.6.e49942

Figure 1 The two levels hypothesis. The colorful horizontal lines represent the duration of high activity in individual columns. The vertical lines show the time relation to the alpha waves. The distance between two neighboring lines is the wavelength, and the green symbols indicate that some waves are a little bit shorter than other waves.