A Comparative Study of Movement Bout Organization in Preterm Human Infants, Norway Rats, and Spiny Mice

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Spontaneous movement, prior to birth, can be observed in the fetuses of all vertebrate species. Although the motor activity of animal and human fetuses subjectively appears random, quantitative analysis has revealed that fetal movements are organized in time and space. Moreover, the temporal and spatial organization evident in fetal motor activity continues to be expressed by animal and human infants after birth. In the present study, we compared the prenatal development of spontaneous limb activity in three species: Norway rats (Rattus norvegicus), spiny mice (Acomys cahirinus), and preterm human infants. Rats bear altricial young, which are born relatively immature, whereas spiny mice are precocial, their offspring exhibiting mature locomotion within 24 hr after birth. Both rodent species were studied using procedures that involve surgical preparation of the pregnant mother to facilitate direct visualization of fetal behavior. In order to study the potential presence of altricial and precocial aspects of development in preterm infants, the spontaneous movement of 25 human subjects born between 25±28 weeks post-conception, were videotaped at weekly intervals in an NICU environment. All three species showed a significant tendency for limb movements to be organized into discrete multilimb bouts, with the movement of any one limb significantly increasing the probability of movement in another limb. These comparative findings indicate that the development of spontaneous motor activity may exhibit very similar patterns of organization, and by inference, similar underlying mechanisms, in fetal rodents and preterm human infants.


Abstract from the 33rd Annual Meeting of the International Society for Developmental Psychobiology, New Orleans, LA, November 1-4, 2000.



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