title: Effect of tactile stimulation on primary motor cortex excitability during action observation combined with motor imagery.
abstract: We aimed to investigate the effects of the tactile stimulation to an observer's fingertips at the moment that they saw an object being pinched by another person on the excitability of observer's primary motor cortex (M1) using transcranial magnetic stimulation (TMS). In addition, the above effects were also examined during action observation combined with the motor imagery. Motor evoked potentials (MEP) were evoked from the subjects' right first dorsal interosseous (FDI) and abductor digiti minimi (ADM) muscles. Electrical stimulation (ES) inducing tactile sensation was delivered to the subjects' first and second fingertips at the moment of pinching action performed by another person. Although neither the ES nor action observation alone had significant effects on the MEP amplitude of the FDI or ADM, the FDI MEP amplitude which acts as the prime mover during pinching was reduced when ES and action observation were combined; however, no such changes were seen in the ADM. Conversely, that reduced FDI MEP amplitude was increased during the motor imagery. These results indicated that the M1 excitability during the action observation of pinching action combined with motor imagery could be enhanced by the tactile stimulation delivered to the observer's fingertips at the moment corresponding to the pinching being observed.
authors.affiliation: Human Motor Control Laboratory, Graduate School of Integrated Arts and Sciences, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima 739-8521, Japan.
authors.forename: Megumi
authors.initials: M
authors.lastname: Tanaka
authors.affiliation: Human Motor Control Laboratory, Graduate School of Integrated Arts and Sciences, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima 739-8521, Japan; Research Fellow of the Japan Society for the Promotion of Science, Japan.
authors.forename: Shinji
authors.initials: S
authors.lastname: Kubota
authors.affiliation: Human Motor Control Laboratory, Graduate School of Integrated Arts and Sciences, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima 739-8521, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Onmyoji
authors.affiliation: Human Motor Control Laboratory, Graduate School of Integrated Arts and Sciences, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima 739-8521, Japan.
authors.forename: Masato
authors.initials: M
authors.lastname: Hirano
authors.affiliation: Human Motor Control Laboratory, Graduate School of Integrated Arts and Sciences, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima 739-8521, Japan; Research Fellow of the Japan Society for the Promotion of Science, Japan.
authors.forename: Kazumasa
authors.initials: K
authors.lastname: Uehara
authors.affiliation: Human Motor Control Laboratory, Graduate School of Integrated Arts and Sciences, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima 739-8521, Japan; Research Fellow of the Japan Society for the Promotion of Science, Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Morishita
authors.affiliation: Human Motor Control Laboratory, Graduate School of Integrated Arts and Sciences, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima 739-8521, Japan. Electronic address: funase@hiroshima-u.ac.jp.
authors.forename: Kozo
authors.initials: K
authors.lastname: Funase
mesh_terms: D000328:Adult; D019054:Evoked Potentials, Motor; D005260:Female; D006801:Humans; D007092:Imagination; D008297:Male; D009039:Motion Perception; D009044:Motor Cortex / Q000502:physiology*; D010812:Physical Stimulation; D014110:Touch; D055815:Young Adult
keywords: Action observation; Motor imagery; Primary motor cortex excitability; Tactile stimulation