Faculty Collaboration Database

Parallel facilitatory reflex pathways from the foot and hip to flexors and extensors in the injured human spinal cord. Exp Neurol 2007 Jul;206(1):146-58

Date

06/05/2007

Pubmed ID

17543951

Pubmed Central ID

PMC1937333

DOI

10.1016/j.expneurol.2007.05.004

Scopus ID

2-s2.0-34250635930 (requires institutional sign-in at Scopus site)   11 Citations

Abstract

Spinal integration of sensory signals associated with hip position, muscle loading, and cutaneous sensation of the foot contributes to movement regulation. The exact interactive effects of these sensory signals under controlled dynamic conditions are unknown. The purpose of the present study was to establish the effects of combined plantar cutaneous afferent excitation and hip movement on the Hoffmann (H) and flexion reflexes in people with a spinal cord injury (SCI). The flexion and H-reflexes were elicited through stimulation of the right sural (at non-nociceptive levels) and posterior tibial nerves respectively. Reflex responses were recorded from the ipsilateral tibialis anterior (TA) (flexion reflex) and soleus (H-reflex) muscles. The plantar cutaneous afferents were stimulated at three times the perceptual threshold (200 Hz, 24-ms pulse train) at conditioning-test intervals that ranged from 3 to 90 ms. Sinusoidal movements were imposed to the right hip joint at 0.2 Hz with subjects supine. Control and conditioned reflexes were recorded as the hip moved in flexion and extension. Leg muscle activity and sagittal-plane joint torques were recorded. We found that excitation of plantar cutaneous afferents facilitated the soleus H-reflex and the long latency flexion reflex during hip extension. In contrast, the short latency flexion reflex was depressed by plantar cutaneous stimulation during hip flexion. Oscillatory joint forces were present during the transition phase of the hip movement from flexion to extension when stimuli were delivered during hip flexion. Hip-mediated input interacts with feedback from the foot sole to facilitate extensor and flexor reflex activity during the extension phase of movement. The interactive effects of these sensory signals may be a feature of impaired gait, but when they are appropriately excited, they may contribute to locomotion recovery in these patients.

Author List

Knikou M, Kay E, Schmit BD

Author

Brian Schmit PhD Professor in the Biomedical Engineering department at Marquette University

MESH terms used to index this publication - Major topics in bold

Adult
Afferent Pathways
Electric Stimulation
Feedback
Female
Foot
Gait Disorders, Neurologic
H-Reflex
Hip Joint
Humans
Male
Mechanoreceptors
Middle Aged
Movement
Muscle, Skeletal
Neural Conduction
Proprioception
Reaction Time
Recovery of Function
Reflex, Abnormal
Spinal Cord Injuries
Sural Nerve
Tibial Nerve
Walking