Research Article

Experimental Brain Research

, Volume 196, Issue 4, pp 529-535

First online:

Influence of touching an object on corticospinal excitability during motor imagery

  • Nobuaki MizuguchiAffiliated withGraduate School of Sport Sciences, Waseda University Email author 
  • , Masanori SakamotoAffiliated withFaculty of Sport Sciences, Waseda University
  • , Tetsuro MuraokaAffiliated withConsolidated Research Institute for Advanced Science and Medical Care, Waseda University
  • , Kazuyuki KanosueAffiliated withFaculty of Sport Sciences, Waseda UniversityConsolidated Research Institute for Advanced Science and Medical Care, Waseda University

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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.


Motor imagery Transcranial magnetic stimulation (TMS) Motor evoked potentials (MEPs) Somatosensory evoked potentials (SEPs)