Spontaneous motility in premature infants: Features of behavioral activity and rhythmic organization

Abstract

The spontaneous motor activity of clinically stable premature infants, 26-36 weeks gestational age, was investigated. Movements were recorded using a pressure-sensitive transducer positioned below the infant's head and torso. Behavior samples were digitized every 0.5 s during 2 and 3-hr continuous recording sessions. Time-series analyses revealed prominent motility cycles of circa 80 min and circa 30 min. These results are consistent with periodicities in motility and REM activation observed in full-term neonates. The longer rhythms of 70-100 min of motility found in this study establish that these periods are present at this stage of development independent of maternal zeitgebers. Developmental changes in motility rhythms and movement burst durations were also observed. Bout durations became somewhat longer in older (> 30 weeks) infants, but the relative time devoted to movement per session was comparable in older and younger (< or = 30 weeks) infants.

Spontaneous movements during sleep in children: Temporal organization and changes with age

“…As we have reported previously in premature infants (Hayes et al, 1993), movements during sleep in children are rhythmic and the dominant period is modified with age. Further analyses of the microstructure of movement bouts revealed that both the frequency and duration are also affected by age.…”

“…Next, the data were collapsed into 1-min bins and each 1-min bin average was compared to the session mean. The average of each bin was assigned a value of 1 or 0 depending on whether it was above or below the session mean (see Hayes et al, 1993). The continuous data stream was divided into bouts according to the following criteria: Bout onset commenced with two consecutive bin averages above the session mean (bin sequence: 1,1), and bout termination was signalled by three consecutive bin averages below the session mean (bin sequence: 0,0,0).…”

Apneic preterms and methylxanthines: arousal deficits, sleep fragmentation and suppressed spontaneous movements

“…Bout duration mean, maximum length across the recording and bout number were calculated using algorithms developed in our laboratory. 11,21 As shown in Table 3, methylxanthine exposure was associated with an increase in the maximum movement bout duration for 60 s epochs for both theophylline and caffeine; while 60 s epoch analyses yielded longer mean bout duration and maximum bout duration for 12 s epochs for caffeine only. Mean movement bout duration in 6 min epochs increased with days of exposure to theophylline.…”

“…Developmental changes in state or movement and quiescence temporal segregation, for example, characteristically longer duration bouts with age, 11 were examined by Pearson's correlations of GA, PMA and days of prior methylxanthine exposure for each group. As expected, PMA correlated significantly with days of prior methylxanthine exposure (theophylline: r(13) ¼ 0.93, P<0.001; caffeine group: r(14) ¼ 0.73, P<0.01; collapsing across both groups: r(27) ¼ 0.84, P<0.001).…”

“…Prematurity, and specifically the 30 to 40 weeks post-menstrual age (PMA), is a critical developmental window for sleep-wake state organization, and the emergence of sustained arousal capacity. [9][10][11][12] Although two laboratories have failed to find effects of methylxanthines on sleep states in the premature, 13,14 behavioral indices of waking and temporal properties of movement were not studied. Thoman et al 12 found increased wake and decreased active sleep 8 weeks after cessation of theophylline treatment in preterm infants.…”