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Short-term effects of functional electrical stimulation on spinal excitatory and inhibitory reflexes in ankle extensor and flexor muscles.
- Source :
-
Experimental brain research [Exp Brain Res] 2006 Apr; Vol. 170 (2), pp. 216-26. Date of Electronic Publication: 2005 Nov 30. - Publication Year :
- 2006
-
Abstract
- The purpose of this study was to investigate short-term effects of walking with functional electrical stimulation (FES) on inhibitory and excitatory spinal reflexes in healthy subjects. The FES was applied to the common peroneal (CP) nerve during the swing phase of the step cycle when the ankle flexors are active. We have previously shown that corticospinal excitability for the tibialis anterior (TA) muscle increased after 30 min of FES-assisted walking. An increase of corticospinal excitability could be due to the changes in spinal and/or cortical excitability. Thus, we wished to examine whether a short-term application of FES would increase spinal motoneuronal excitability. Changes could also result from effects on inhibitory as well as excitatory pathways, but to our knowledge no studies have investigated short-term effects of FES on spinal inhibitory pathways. Therefore, we measured reciprocal and presynaptic inhibition, as well as reflex excitability, before and after FES-assisted walking. As controls, effects of FES-like stimulation at rest and walking without stimulation were tested in separate sessions. The TA H-reflex amplitude did not increase after FES in any of the conditions tested, so we have no evidence that FES increases spinal excitability for the TA. The soleus H-reflex decreased slightly (10%) after FES-assisted walking, and remained decreased for at least 30 min. However, the control experiment indicated that this decrease was associated with walking and not with stimulation. Thirty minutes of FES did not produce any significant effects on spinal inhibitory pathways examined in the present study. In conclusion, the soleus H-reflex showed a small but consistent decrease and no spinal circuits examined showed an increase, as was observed in the corticospinal excitability. Thus, we suggest that a short-term application of FES increases the excitability of the cortex or its connections to the spinal cord more effectively than that of spinal pathways.
- Subjects :
- Adult
Efferent Pathways physiology
Electric Stimulation methods
Excitatory Postsynaptic Potentials physiology
Gait physiology
H-Reflex physiology
Humans
Middle Aged
Motor Cortex physiology
Motor Neurons physiology
Muscle Contraction physiology
Peroneal Nerve physiology
Pyramidal Tracts physiology
Time Factors
Ankle physiology
Muscle, Skeletal innervation
Muscle, Skeletal physiology
Neural Inhibition physiology
Reflex physiology
Spinal Cord physiology
Subjects
Details
- Language :
- English
- ISSN :
- 0014-4819
- Volume :
- 170
- Issue :
- 2
- Database :
- MEDLINE
- Journal :
- Experimental brain research
- Publication Type :
- Academic Journal
- Accession number :
- 16317575
- Full Text :
- https://doi.org/10.1007/s00221-005-0203-y