The overall goal of this research is to determine how conflicting visual and self-motion information modulates the responses of the postural control system in elderly adults and in individuals post-stroke. When visual field information does not match self-motion feedback, healthy elderly respond to combined visual, vestibular, and proprioceptive signals differently than young adults. Young adults incorporate frequency components of all inputs into their responses;elderly adults rely primarily on vision. We hypothesize that elderly adults and individuals post-stroke have increased sensory thresholds to complex multimodal stimuli which produces a greater reliance on predictive or on visual inputs making it more difficult for them to selectively respond to visual and physical destabilization. By combining the technology of a virtual environment with support surface translations we plan to manipulate the influence of visual inputs, somatosensory (i.e., proprioceptive and vestibular) inputs, and prediction to reveal the contribution of segmental inputs and higher order processing to the postural response. We plan to compare healthy young and elderly individuals with young and elderly individuals post-stroke in order to distinguish between the effects of age and CNS impairment. We will first explore whether subjects change their responses to particular sensory modalities over time. Then the head and trunk will be aligned in different positions with respect to visual and support surface motion to reveal how altering sensory and biomechanical orientations affects the response to visual motion signals. Lastly, we will examine how predictable and random visual inputs influence the response to random support surface inputs. Visual field dependence will be measured with a Rod and Frame test. We will employ novel methods of Principal Component Analysis and autoregressive modeling to distinguish between body mechanics and specified neural processes. These analyses should reveal how the selection of control pathways is determined by the task as well as further define response properties of the afferent pathways. Segmental and muscle response strategies will be examined through kinematic measures including center of pressure, center of mass displacement, and electromyography, and tested for significance with a MANOVA. Clarifying the relation between visual inputs and postural stabilization will identify functional situations that present a high probability for instability and falling. Results from the proposed studies can potentially be used for developing individually designed programs of therapeutic intervention.

Agency
National Institute of Health (NIH)
Institute
National Institute on Aging (NIA)
Type
Research Project (R01)
Project #
5R01AG026470-04
Application #
7670243
Study Section
Musculoskeletal Rehabilitation Sciences Study Section (MRS)
Program Officer
Chen, Wen G
Project Start
2006-09-15
Project End
2012-08-31
Budget Start
2009-09-01
Budget End
2012-08-31
Support Year
4
Fiscal Year
2009
Total Cost
$286,583
Indirect Cost
Name
Temple University
Department
Other Health Professions
Type
Schools of Allied Health Profes
DUNS #
057123192
City
Philadelphia
State
PA
Country
United States
Zip Code
19122
Keshner, Emily A; Slaboda, Jill C; Day, Lois Lanaria et al. (2014) Visual conflict and cognitive load modify postural responses to vibrotactile noise. J Neuroeng Rehabil 11:6
Haran, F J; Tierney, R; Wright, W G et al. (2013) Acute changes in postural control after soccer heading. Int J Sports Med 34:350-4
Slaboda, Jill C; Keshner, Emily A (2012) Reorientation to vertical modulated by combined support surface tilt and virtual visual flow in healthy elders and adults with stroke. J Neurol 259:2664-72
Slaboda, Jill C; Lauer, Richard T; Keshner, Emily A (2011) Continuous visual field motion impacts the postural responses of older and younger women during and after support surface tilt. Exp Brain Res 211:87-96
Wright, W G (2011) Tonic postural lean after-effects influenced by support surface stability and dynamics. Hum Mov Sci 30:238-48
Slaboda, Jill C; Lauer, Richard; Keshner, Emily A (2011) Time series analysis of postural responses to combined visual pitch and support surface tilt. Neurosci Lett 491:138-42
Wang, Yun; Kenyon, Robert V; Keshner, Emily A (2010) Identifying the control of physically and perceptually evoked sway responses with coincident visual scene velocities and tilt of the base of support. Exp Brain Res 201:663-72
Keshner, Emily A; Kenyon, Robert V (2009) Postural and spatial orientation driven by virtual reality. Stud Health Technol Inform 145:209-28
Dokka, Kalpana; Kenyon, Robert V; Keshner, Emily A (2009) Influence of visual scene velocity on segmental kinematics during stance. Gait Posture 30:211-6
Slaboda, J C; Barton, J E; Maitin, I B et al. (2009) Visual field dependence influences balance in patients with stroke. Conf Proc IEEE Eng Med Biol Soc 2009:1147-50

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