The long-term goal of the work proposed here is to understand the production and change over time in patterns of motor behavior. The studies are informed by a dynamic systems perspective and expand the use of mathematical models that address coordination issues by focusing on the availability of dynamic resources from which humans select control strategies for solving movement problems. Recently such a model has been developed but limited in its validation to normal children and those with cerebral palsy (CP). This proposal addresses the generalizability of this modeling approach by focusing on a population with unique dynamic resources, Down syndrome (DS). It extends previous work by studying behavior across the lifespan in a population whose control problems are poorly understood. Focus is on walking because it emerges relatively early in life, is well practiced over time, complex, changes over the lifespan, is an important functional skill, yet has received limited directed attention by the scientific community.
Specific aim #1 is to examine the capacity of the model to explain gait pattern differences in preadolescent children with DS and typically developing (TD) children as well as their ability to adapt to perturbations. Preadolescence is a time when performance on this task may be expected to be optimal. Comparison will be made between gait kinematics and the model's predicted dynamic gait strategies (i.e., relative stiffness and forcing functions.
Specific aim #2 is to extend the application of this model across developmental levels, including new walkers and older walkers. At these levels optimality constraints may be quite different; they represent different levels of practice, as well as differences in the biomechanical and physiological constraints, within the same population. In particular, new walkers will be tested in a longitudinal study design in order to map the emergence of dynamic strategies within participants.
Specific aim #3 is to concurrently validate the effectiveness of the model. This will include comparing the model's method for estimating stiffness and forcing to measures developed by other researchers, examining neuromuscular correlates of the model's estimates for stiffness and forcing, and determining if non-linear components in the model are required to minimize the error and maximize generalizability of the model. These studies have wide-ranging implications for a.) understanding the emergence of control strategies, b.) understanding general processes of change, and c.) impacting on clinical practice, especially physical and occupational therapy and orthopaedic medicine.

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Research Project (R01)
Project #
5R01HD042728-04
Application #
6914449
Study Section
Special Emphasis Panel (ZRG1-BBBP-7 (01))
Program Officer
Quatrano, Louis A
Project Start
2002-08-01
Project End
2006-07-31
Budget Start
2005-08-01
Budget End
2006-07-31
Support Year
4
Fiscal Year
2005
Total Cost
$171,832
Indirect Cost
Name
University of Michigan Ann Arbor
Department
Miscellaneous
Type
Other Domestic Higher Education
DUNS #
073133571
City
Ann Arbor
State
MI
Country
United States
Zip Code
48109
Smith, Beth A; Kubo, Masayoshi; Ulrich, Beverly D (2012) Gait parameter adjustments for walking on a treadmill at preferred, slower, and faster speeds in older adults with down syndrome. Curr Gerontol Geriatr Res 2012:782671
Mulvey, Genna M; Kubo, Masayoshi; Chang, Chia-Lin et al. (2011) New walkers with Down syndrome use cautious but effective strategies for crossing obstacles. Res Q Exerc Sport 82:210-9
Smith, Beth A; Stergiou, Nicholas; Ulrich, Beverly D (2011) Patterns of gait variability across the lifespan in persons with and without down syndrome. J Neurol Phys Ther 35:170-7
Smith, Beth A; Ashton-Miller, James A; Ulrich, Beverly D (2010) Gait adaptations in response to perturbations in adults with Down syndrome. Gait Posture 32:149-54
Smith, Beth A; Stergiou, Nick; Ulrich, Beverly D (2010) Lyapunov exponent and surrogation analysis of patterns of variability: profiles in new walkers with and without down syndrome. Motor Control 14:126-42
Chang, Chia-Lin; Kubo, Masayoshi; Ulrich, Beverly D (2009) Emergence of neuromuscular patterns during walking in toddlers with typical development and with Down syndrome. Hum Mov Sci 28:283-96
Black, D; Chang, C-L; Kubo, M et al. (2009) Developmental trajectory of dynamic resource utilization during walking: toddlers with and without Down syndrome. Hum Mov Sci 28:141-54
Smith, Beth A; Ulrich, Beverly D (2008) Early onset of stabilizing strategies for gait and obstacles: older adults with Down syndrome. Gait Posture 28:448-55
Black, David P; Smith, Beth A; Wu, Jianhua et al. (2007) Uncontrolled manifold analysis of segmental angle variability during walking: preadolescents with and without Down syndrome. Exp Brain Res 183:511-21
Holt, Kenneth G; Saltzman, Elliot; Ho, Chia-Ling et al. (2007) Scaling of dynamics in the earliest stages of walking. Phys Ther 87:1458-67

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