The monosynaptic reflex: a tool to investigate motor control in humans. Interest and limits.
The principle of the monosynaptic reflex used as a tool to explore the excitability of the motoneurones (MNs) is explained and the general methodology of the H reflex is described. The different drawbacks inherent in the technique are then considered: mechanisms other than the monosynaptic la excitation of MNs contributing to the H reflex size (limitation of the H reflex size by disynaptic IPSPs, presynaptic inhibition of la terminals, post-activation depression); non-linearity and changes in the 'recruitment gain' in the MN pool; and poor time resolution of the method. Despite these drawbacks, it is emphasized that the H reflex is the only available technique enabling one to investigate changes in transmission in spinal pathways during motor tasks.
Pierrot-Deseilligny
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Laboratoire de neurophysiologie clinique, rééducation, hôpital de la Salpêtrière, Paris, France.
Mazevet
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D
D000818:Animals; D003213:Conditioning, Psychological; D004558:Electric Stimulation; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D006181:H-Reflex / Q000502:physiology*; D006801:Humans; D009046:Motor Neurons / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology; D009434:Neural Pathways; D017729:Presynaptic Terminals / Q000502:physiology; D011930:Reaction Time / Q000502:physiology; D011999:Recruitment, Neurophysiological / Q000502:physiology*; D012023:Reflex, Monosynaptic / Q000502:physiology