Figure 3. Frequency modulation effects of spiral waves.

In A and B, top trace: Raw recording signal from a representing optical detector. Middle image: the frequency-time map (frequency spectrum) made from that detector. Fast Fourier transform was used to analyze the power spectrum of signals in a sliding window of 300 ms. Pseudocolor scale: relative power of the frequency components, red for high (1) and blue for low (0) power. Bottom images: selected from the phase movie for identifying wave patterns. Broken vertical lines indicate the times for these images. The red broken lines mark the first cycle of spiral waves and black arrows mark the end of spiral waves. A. An oscillation segment contains a long-lasting spiral waves (7 rotations). The frequency-time map shows that the oscillation frequency increases to a higher frequency during spiral waves. Three additional examples are shown in Figure S3A-C. B. Ongoing cortical activity during the theta-dominant period of sleep-like state, a pair of short-lived spiral waves was identified by phase maps (bottom images). Similar effects are observed during spiral waves. Three additional examples are shown in Figure S3D-F. C. Distribution of frequencies during spiral waves and all wave patterns in Cch/bic induced oscillations. Fast Fourier transform was used to analyze the power spectrum of signals with spiral waves or randomly chosen segments of signals, and the frequency corresponding to the major peak was used. D. Frequency distribution of spiral waves and other periods during sleep-like states.