[Morphophysiological analysis of the formation of mechanisms of the activity-rest cycle in human ontogenesis].

The natural behavior of normal and anencephalic fetuses at 20 to 41 weeks of the development was studied by ultrasound monitoring and continuous recording of heart rate (HR) and motor activity (MA), followed by processing and presentation on [symbol: see text]CM computer. The statistical characteristics of HR and MA changes in the anencephalic fetuses were corrected by the degree of CNS deficiency. The comparative study of 20 normal and 34 anencephalic fetuses showed: 1) when the spinal cord was present, stable HR (about 150 bpm) seems to be due to cardiac automatism and sharp decelerations unaccompanied by MA were recorded; 2) in fetuses with the medulla oblongata present showed a decrease in baseline HR up to 140 bpm, repeated pronounced decelerations and spontaneous single motor acts dissociated with the latter; 3) when a rudiment of the midbrain was present, some reductions in the amplitude of decelerations and manifestation of weak accelerations, cluster motor acts, brief episodes of the active state were revealed; 4) the quiet state was observed in fetuses with the cerebral cortex; 5) the rest-activity cycle formed with further differentiation of the cerebral cortex.

[The temporal organization of human fetal motor function].

Fetal motor bursts were recorded in pregnant women at 11-18, 20-24 and 30-32 weeks of pregnancy. It was stated that spontaneous motor activity in human fetus is similar to autogenic periodic motor excitation observed in other species of vertebrates, i.e.

[Development of the activity-rest cycle in the human fetus].

Some features of natural fetal behavior (general motor activity, including respiratory activity, heart rate and the motor-cardiac reflex as their correlated function) were studied by means of ultrasound scanning, monitoring and dynamic cardiography in 96 women at 20 to 36 weeks of pregnancy under continuous recording of physiological parameters for 2-3 hours. Computer analysis of heart rate variation in correlation with body movements has revealed that there is only one functional state in the fetal behavior, called "nondifferentiated state" (NDS), by the 20th week of pregnancy. Against this background, there appear transitory episodes of active state beginning from the 21st week, and those of quiet state, from the 23rd week; duration of the episodes increases with the progress of pregnancy.