Education:
BS 1975 Physical Therapy - University of Southern California
MS 1983 Kinesiology - University of California, Los Angeles
PhD 1986 Kinesiology - University of California, Los Angeles
Postdoctoral Research Fellowship:
1986 - 1988 University of Colorado, Boulder
Started at USC: 1992
Research Topics: Behavioral Neurobiology, Developmental Psychobiology, Sensorimotor physiology
Research Description
Development and control of repetitive leg movements during embryonic development
Our long-term objectives are to determine if fetal movements and the environment in which they are generated contribute to adaptive postnatal motor behavior. New imaging technologies are revealing ever greater details of motor behavior in the fetus for clinical diagnosis and treatment. Understanding the form, mechanisms and significance of fetal behavior will be important for maximizing clinical application of these tools. Evidence indicates fetal movement is essential for differentiating musculoskeletal structures, and may also be useful in identifying a potential medical crisis, but it is not known if specific complex movements reliably distinguish states of neurodevelopment or if they shape the neonatal motor repertoire. Results of our studies will provide fundamental information relevant to questions of prenatal experience, environmental impact on the control of prenatal limb movements during both normal development in utero and when environmental forces are altered by extremely premature birth.
Our model for prenatal motor development is the chick embryo. Like the human fetus, the chick embryo begins generating complex movements such as kicking and stepping early in development. The chick embryo is a valuable model of fetal behavior because it is amenable to combinations of behavioral, physiological, pharmacological and neuroanatomical study throughout embryonic development. Our recent studies provide evidence that leg stepping in the last 3 days before hatching is produced by neural circuits that control leg movements during locomotion. Our current studies are exploring the impact of muscle proprioception and light-induced acceleration of development during embryogenesis on control of stepping movements prior to hatching and bipedal locomotion. Our studies will provide fundamental insights into the impact of gravity and intense light exposure on motor control when the infant is born prematurely and is exposed to conditions commonly associated with neonatal intensive care.
10 Selected Publications:
Click here to view all the publications for this faculty
Bradley NS - Reduction in buoyancy alters parameters of motility in E9 chick embryos. - Physiol Behav [1997] Sep;62(3):591-5 PubMed
Ryu YU,Bradley NS - Precocious locomotor behavior begins in the egg: development of leg muscle patterns for stepping in the chick. - PLoS One [2009] Jul 3;4(7):e6111 PubMed
Bradley NS,Ryu YU,Lin J - Fast locomotor burst generation in late stage embryonic motility. - J Neurophysiol [2008] Apr;99(4):1733-42 PubMed
Bradley NS,Solanki D,Zhao D - Limb movements during embryonic development in the chick: evidence for a continuum in limb motor control antecedent to locomotion. - J Neurophysiol [2005] Dec;94(6):4401-11 PubMed
Oztop E,Bradley NS,Arbib MA - Infant grasp learning: a computational model. - Exp Brain Res [2004] Oct;158(4):480-503 PubMed
Bradley NS - Connecting the dots between animal and human studies of locomotion. Focus on "Infants adapt their stepping to repeated trip-inducing stimuli". - J Neurophysiol [2003] Oct;90(4):2088-9 PubMed
Bradley NS,Jahng DY - Selective effects of light exposure on distribution of motility in the chick embryo at E18. - J Neurophysiol [2003] Sep;90(3):1408-17 PubMed
Bradley NS - Age-related changes and condition-dependent modifications in distribution of limb movements during embryonic motility. - J Neurophysiol [2001] Oct;86(4):1511-22 PubMed
Bradley NS,Sebelski C - Ankle restraint modifies motility at E12 in chick embryos. - J Neurophysiol [2000] Jan;83(1):431-40 PubMed
Bradley NS - Transformations in embryonic motility in chick: kinematic correlates of type I and II motility at E9 and E12. - J Neurophysiol [1999] Apr;81(4):1486-94 PubMed
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