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H-reflex Methods and Significance

H-reflex Methods and Significance. Chetan Phadke, P.T., Ph.D. Post-doctoral Fellow, Mentor: Carolynn Patten Neural Control Movement Lab VA, BRRC. Monosynaptic reflex pathway. H-reflex. Paul Hoffmann first described it in 1910 Electrical analog of stretch reflex

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H-reflex Methods and Significance

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  1. H-reflex Methods and Significance Chetan Phadke, P.T., Ph.D. Post-doctoral Fellow, Mentor: Carolynn Patten Neural Control Movement Lab VA, BRRC

  2. Monosynaptic reflex pathway

  3. H-reflex • Paul Hoffmann first described it in 1910 • Electrical analog of stretch reflex • By-passes muscle spindle and Gamma • Direct sensory fiber (Ia) electrical stimulation

  4. The H-reflex Muscle Spindle Ia α H-reflex Muscle M-wave Stimulus Artifact Courtesy: University of Louisville (Dept. of Neurosurgery) and Frazier Rehab.

  5. Window into Spinal Cord • Enables study of spinal excitability • Excitability is regulated by inhibition from supraspinal and sensory flow • The level of inhibition on the H-reflex determines the amplitude • Easily evoked in most muscles • Soleus widely studied Palmieri (2004), Zehr (2001)

  6. Functional Significance • Greater in Sitting than Standing • Greater in stance phase than swing • Pedaling modulation similar to walking • Arm swing and arm cycling alter soleus H-reflex • Walking on a narrow beam • Gymnasts Capaday (1987), Trimble (2001), Phadke (2007), Boorman (1992), Zehr (2001), Llewellyn (1990),

  7. Phase dependent H–reflex modulation

  8. H-reflex post-SCI Non-injured SCI 5V 31.25 ms

  9. Functional Correlation • Greater amplitude post-SCI and slower ground walking speed • Single LT and bicycling session: Smaller reflexes in walking and semi-reclined and increased ground walking speed • Long-term LT resulted in smaller reflexes in walking and faster ground walking speed Trimble (2001), Phadke (2009), Behrman (2008 - unpublished)

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