Vibration-induced presynaptic inhibition of the soleus H reflex is temporarily reduced by cortical magnetic stimulation in human subjects.
We have examined the effects of a transcranial magnetic stimulus (TMS) on the H reflex of the soleus muscle during vibration-induced presynaptic inhibition of the reflex, in seven normal volunteers. Without vibration, the H reflex was facilitated at interstimulus time intervals of > or = 5 ms after TMS. With vibration, the H reflex was markedly reduced or completely inhibited in control trials, but facilitation by TMS was noticed at intervals as short as -2.5 ms. These findings indicate an effect of TMS on the spinal interneurons mediating presynaptic vibratory inhibition of the H reflex.
Valls-Sole
J
J
Unitat d'EMG, Hospital Clinic i Provincial, Barcelona, Spain.
Alvarez
R
R
Tolosa
E S
ES
D002540:Cerebral Cortex / Q000502:physiology*; D004558:Electric Stimulation; D006181:H-Reflex / Q000502:physiology*; D006801:Humans; D007395:Interneurons / Q000502:physiology; D008280:Magnetics; D009132:Muscles / Q000294:innervation* / Q000502:physiology; D009475:Neurons, Afferent / Q000502:physiology; D017661:Receptors, Presynaptic / Q000502:physiology*; D014732:Vibration / Q000009:adverse effects*
D017661:Receptors, Presynaptic