Temporal Patterning of Spontaneous Motor Activity in Altricial and Precocial Rodent Fetuses and Preterm Human Infants: a Comparative Study of Bout Organization and Interlimb Movement Synchrony

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While spontaneous movement is a ubiquitous feature of fetal development, little is known about the temporal organization of this early behavior, or the relationship between these early movements and subsequent coordination of the developing nervous system. To investigate these patterns, two measures of spontaneous movement were applied in a comparative design of development. The first measure, bout organization, assesses the probability of successive limb movements, after the movement of any one limb. To describe the movement relationships between specific limbs, a second measure, interlimb movement synchrony also was studied. With this analysis, profiles of the temporal relationship of limb movement are investigated in a pairwise manner. In order to determine if the results from these measures represented general mechanisms of nervous system development, or merely species specific patterns, two species of rodent fetuses were compared by direct observation. One is altricial (Norway rat, Rattus norvegicus), bearing immature young, and the other is precocial (spiny mouse, Acomys cahirinus), whose young exhibit mature locomotion within 24 hours of birth. A third species, premature human infants, also were studied from 28-37 weeks post conception. These human subjects were videotaped at weekly intervals in the Neonatal Care Unit of the University of Iowa Hospitals and Clinics in collaboration with the Clinical Research Center. Results revealed patterns that were generalizable across all species. However, species specific patterns of these measures also were evident. Overall, the continuity of patterns across species suggests that measures of spontaneous movement may help to identify common mechanisms in the development of mammalian nervous systems.


Abstract of poster presented at the 33rd Annual Meeting of the Society for Neuroscience, New Orleans, LA, November 8-12, 2003.