Supraspinal inputs reduce corticomotor excitability during passive movement: evidence from a pure sensory stroke.
Corticomotor excitability is reduced during rhythmic passive movement compared to rest, but it is not known whether the mechanism is purely segmental or includes a supraspinal pathway. To determine how interruption of sensory projections at a supraspinal level affects corticomotor excitability during passive movement, we measured the amplitude of motor evoked potential (MEP) during 1 Hz cyclic index finger movements in a patient with a brainstem and thalamus lesion that resulted in a pure sensory stroke. Measurements of MEP amplitude and proprioception were made 14 and 64 days post-stroke. In the first study, when subjective position sense was reduced for the index finger, MEP amplitude was significantly increased during passive movement compared to rest (4.6+/-0.2 SEM mV vs. 4.0+/-0.2 mV; p=0.0281). However in the second study, when position sense had returned to normal, MEP amplitude was significantly reduced during movement compared to rest (6.2+/-0.3 mV vs. 6.6+/-0.1 mV; p=0.0224). These observations provide evidence that supraspinal sensory pathways are involved in reducing corticomotor excitability during rhythmic passive movement.
Edwards
D J
DJ
Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Australia. d.edwards@ecu.edu.au
Mastaglia
F L
FL
Byrnes
M L
ML
Fregni
F
F
Pascual-Leone
A
A
Thickbroom
G W
GW
D000704:Analysis of Variance; D004558:Electric Stimulation; D019054:Evoked Potentials, Motor / Q000502:physiology; D018737:Hand Strength; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology*; D009068:Movement / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology / Q000528:radiation effects; D011712:Pyramidal Tracts / Q000503:physiopathology*; D020521:Stroke / Q000473:pathology* / Q000503:physiopathology*; D013997:Time Factors; D050781:Transcranial Magnetic Stimulation / Q000379:methods