Influence of touching an object on corticospinal excitability during motor imagery.
We investigated whether corticospinal excitability during the imagery of an action involving an external object was influenced by actually touching the object. Corticospinal excitability was assessed by monitoring motor evoked potentials (MEPs) in the first dorsal interosseous muscle following transcranial magnetic stimulation over the motor cortex during imagery of squeezing a ball-with or without passively holding the ball. The MEPs amplitude during imagery when the ball was held was larger than that when the ball was not held. The MEPs amplitude was not modulated just by holding the ball. In the same experimental condition, the somatosensory evoked potentials (SEPs) in response to the stimulation of median nerve were not modulated by motor imagery or by holding the ball. These results suggest that the corticospinal excitability during imagery of squeezing a ball is enhanced with the real touch of the ball, and the enhancement would be caused by some changes along the corticospinal pathway itself and not by the change in responsiveness along the afferent pathway to the primary somatosensory cortex.
Mizuguchi
Nobuaki
N
Graduate School of Sport Sciences, Waseda University, 2-579-15 Mikajima, Tokorozawa, Saitama, 359-1192, Japan. mizuguchi@suou.waseda.jp
Sakamoto
Masanori
M
Muraoka
Tetsuro
T
Kanosue
Kazuyuki
K
D000328:Adult; D000344:Afferent Pathways / Q000502:physiology; D001931:Brain Mapping; D004569:Electroencephalography; D019054:Evoked Potentials, Motor / Q000502:physiology; D005073:Evoked Potentials, Somatosensory / Q000502:physiology; D005385:Fingers / Q000294:innervation / Q000502:physiology; D006801:Humans; D007092:Imagination / Q000502:physiology*; D008297:Male; D008465:Mechanoreceptors / Q000502:physiology; D008475:Median Nerve / Q000502:physiology; D008875:Middle Aged; D009044:Motor Cortex / Q000502:physiology*; D009068:Movement / Q000502:physiology*; D018482:Muscle, Skeletal / Q000294:innervation / Q000502:physiology; D009431:Neural Conduction / Q000502:physiology; D009434:Neural Pathways / Q000502:physiology; D009483:Neuropsychological Tests; D011597:Psychomotor Performance / Q000502:physiology*; D011712:Pyramidal Tracts / Q000502:physiology*; D013003:Somatosensory Cortex / Q000502:physiology; D014110:Touch / Q000502:physiology; D055698:Touch Perception / Q000502:physiology*; D050781:Transcranial Magnetic Stimulation; D055815:Young Adult