Short-time Fourier Transform (STFT) analysis. The figure illustrates the STFT analysis of signal of dynamic pixels in every 0.5 sec along time. The time interval for each analysis is 1 sec. Intensity of green colour is corresponding to the power value while the red colour indicates the fbasic. (A) Control embryo showed consistent fbasic during the examination period. In contrast, the fbasic varied time by time in terfenadine-treated embryos, no matter in embryo with (B) decreased heart rate or (C) normal heart rate.