Figure 3: Continuous wavelet transform (CWT) analysis of slow-wave activity and segmentation.

(a) Intracellular electrical activity of circular muscle in the presence decanoic acid (1 mM). MP, membrane potential. (b) Time–frequency contour plot of mean power (CWT analysis) shows a high-frequency component (~32 cycles per min) with a low-frequency component (~3 cycles per min) in source signal a. Red and blue indicate a power increase or decrease, respectively. (c) Fourier transform (FFT) analysis of signal a shows complete frequency distribution of source signal (blue) and filtered low-frequency signal (red). (d) Signal filtering shows the presence of a low oscillatory activity in the source signal (a). Note that high-frequency power in b is time-locked to the trough of the filtered low-frequency signal in d. MP, membrane potential. (e) Diameter changes over time obtained from the spatio–temporal map (amplitude profile) in the presence of decanoic acid at one point along the intestine. (f) Time–frequency contour plot of mean power of source signal (e) (CWT analysis) shows the high-frequency (~38 cpm) signal amplitude with significant low-frequency signals throughout (~5 c.p.m). Red and blue indicate a power increase or decrease, respectively. (g) FFT analysis of signal (e) shows complete frequency distribution of source signals (blue) and filtered low-frequency signals (red). (h) Significant low-frequency signal shows after filtering source signal (e). Note that high-frequency power in f is time-locked to the trough of the filtered low-frequency signal in h. The low frequency is not stationary.