Intrinsic temporal patterning in the spontaneous movement of awake neonates.

The temporal organization of spontaneous movement in healthy, awake neonates was studied on the second or third day after birth. Movement was recorded using time lapse photography and quantified as a function of time. Fourier analysis was then used to partition the total variance of each neonate's time-based data into independent components in the frequency domain. Tests on the resulting cumulative variance distributions indicated that the fluctuations in movement over time were not random. Smoothed spectral density functions were then computed to isolate the dominant rhythms. Spectral peaks occurred in the region between .24 and 1.86 cycles per min, indicating the presence of rhythms in general motility with an average frequency (across babies) of .69 cycles per min. These findings are evidence of intrinsic temporal organization at frequencies very different from previously documented rhythms in newborn behavior and physiology.