Elise Walker SfN 2015
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ACKNOWLEDGEMENTS 067. Heightened attention to proprioceptive feedback is not sufficient for long-latency reflex modulation during arm posture. E.H.E. Walker 1,4 R. Ruiz-Torres 2 L.E. Miller 1,2,3 E.J. Perreault 1,3,4 1 Biomedical Engineering, 2 Physiology, 3 Physical Medicine and Rehabilitation, Northwestern University, Evanston (Chicago), IL 4 Sensory Motor Performance Program, Rehabilitation Institute of Chicago, Chicago, IL INTRODUCTION This work was done in conjunction with Northwestern University and the Sensory Motor Performance Program and was supported in part by the NSF grant 0932263 and NIH grant NS053813-08. The authors would like to thank Timothy Haswell for his help with the experimental setup. CONCLUSIONS METHODS 3 Attention Conditions: • Propriocep tive (bumps) • Visual (dots) • Control (none) 3 Measurements: • Stretch reflexes (20% perturbation trials) • H-reflexes (electrical stimulation of median nerve) • SEPs - Somatosensory Evoked Potentials (C3’ ref Fpz’) • Stretch reflexes are important for postural stability in the arm. • Long-latency stretch reflexes become more sensitive in unstable environments. • It is not clear what factors drive long-latency reflex modulation as seen in different environments. • Hypothesis: Heightened attention to proprioceptive feedback drives this type of reflex modulation. more stable less stable Perreault et al. 2008, J Neurophysiology: Adaptive stimulus intensities ensured selective attention Stretch reflexes were not significantly influenced by attention H-reflexes and SEPs were not significantly influenced by attention Post-hoc Power Analysis • The output of reflex loops, sensitivity of spinal circuitry, and the strength of ascending sensory information are not affected by attention in this task. • Attention alone is insufficient to accomplish long-latency reflex modulation during posture. • Engagement with novel environmental dynamics may be key to long-latency reflex modulation. BGA: F≤1.56 p≥0.24 SLR : F≤2.58 p≥0.11 LLR1: F≤0.46 p≥0.64 LLR2: F≤1.91 p≥0.20 • ANOVA with alpha = 0.05 and sample size = 9 • Estimated effect size = 1.5 to 4.0 • Based on Perreault et al. 2008, Shemmell et al. 2009, Krutky et al. 2010 • Statistical power ≥ 87%
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Transcript of Elise Walker SfN 2015
ACKNOWLEDGEMENTS
067. Heightened attention to proprioceptive feedback is not sufficient for long-latencyreflex modulation during arm posture. E.H.E. Walker1,4 R. Ruiz-Torres2 L.E. Miller1,2,3 E.J. Perreault1,3,4
1Biomedical Engineering, 2Physiology, 3Physical Medicine and Rehabilitation, Northwestern University, Evanston (Chicago), IL4Sensory Motor Performance Program, Rehabilitation Institute of Chicago, Chicago, IL
INTRODUCTION
This work was done in conjunction with Northwestern University and the Sensory Motor Performance Program and was supported in part by the NSF grant 0932263 and NIH grant NS053813-08. The authors would like to thank Timothy Haswell for his help with the experimental setup.
CONCLUSIONS
METHODS3 Attention Conditions:• Proprioceptive
(bumps)• Visual
(dots)• Control
(none)
3 Measurements:• Stretch reflexes (20% perturbation trials)• H-reflexes (electrical stimulation of median nerve)• SEPs - Somatosensory Evoked Potentials (C3’ ref Fpz’)
• Stretch reflexes are important for postural stability in the arm.
• Long-latency stretch reflexes become more sensitive in unstable environments.
• It is not clear what factors drive long-latency reflex modulation as seen in different environments.
• Hypothesis: Heightened attention to proprioceptive feedback drives this type of reflex modulation.
more stableless stable
Perreault et al. 2008, J Neurophysiology: Adaptive stimulus intensities ensured selective attention
Stretch reflexes were not significantly influenced by attention
H-reflexes and SEPs were not significantly influenced by attention
Post-hoc Power Analysis
• The output of reflex loops, sensitivity of spinal circuitry, and the strength of ascending sensory information are not affected by attention in this task.
• Attention alone is insufficient to accomplish long-latency reflex modulation during posture.
• Engagement with novel environmental dynamics may be key to long-latency reflex modulation.
BGA: F≤1.56 p≥0.24SLR : F≤2.58 p≥0.11LLR1: F≤0.46 p≥0.64LLR2: F≤1.91 p≥0.20
• ANOVA with alpha = 0.05 and sample size = 9• Estimated effect size = 1.5 to 4.0
• Based on Perreault et al. 2008, Shemmell et al. 2009, Krutky et al. 2010
• Statistical power ≥ 87%
Effect size f
Pow
er (
1-β
err
prob
)
F tests - ANOVA: Fixed effects, special, main effects and interactionsNumerator df = 2, Number of groups = 3, Total sample size = 9, α err prob = 0.05
0.88
0.9
0.92
0.94
0.96
0.98
1
1.5 2 2.5 3 3.5 4
1
0.98
0.96
0.94
0.92
0.90
0.88
Pow
er (1
– β
err
pro
b)
1.5 2 2.5 3.53 4
Effect size
In each trial, the subject attends to a stimulus as directed on the screen.
Dots move more/less randomly. Bump force gets smaller/larger. Direction discrimination maintained at 70-80%
No significant differences at a level of α=0.05 in any time window or any muscle.Stretch reflexes were evoked by perturbations.
Equal BGA and M-wave ensures matched stimulations.No signif. difference in sensitivity of spinal circuits (p=0.32).No signif. difference in ascending sensory signals (p=0.85).
H-reflexes and SEPs were evoked by median nerve stimulation.
ms
ms
