title: The role of handedness-dependent sensorimotor experience in the development of mirroring.
abstract: In daily life, we often try to learn motor actions by imitating others' actions. Motor imitation requires us to simultaneously map an observed action onto a motor program used to perform that action. This sensorimotor associative experience can plastically modulate the mirror property of the human mirror system, which has a role in matching observed actions directly with the observer's motor programs, to enhance the association between observed and performed actions. In the present study, we investigated the effects of handedness on the mirror property. Healthy left- and right-handed individuals performed a motor imitation task. They were required to imitate hand actions with their dominant hand as quickly and accurately as possible in response to pictures of a left and right hand. Reaction times (RTs) for imitating the hand actions were evaluated. Under the condition where the hand pictures were presented as if facing the participant, we found that, in left-handed participants, RTs for imitating right-handed actions were significantly shorter than those for imitating left-handed actions. Under the same conditions in right-handers, similar differences in RTs when presented left- and right-handed actions were not observed. These findings demonstrate that the imitative responses for left- and right-handed actions are differently facilitated depending on the handedness of the observer, indicating an effect of handedness on the development of mirror systems. The mirror property in left- and right-handers is likely modulated in a different manner by different sensorimotor associative experiences throughout their daily lives.
authors.affiliation: Graduate School of Human and Environmental Studies, Kyoto University, Yoshida-nihonmatsu-cho, Sakyo-ku, Kyoto 606-8501, Japan.
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Mori
authors.affiliation: School of Health and Sport Sciences, Osaka University of Health and Sport Sciences, 1-1 Asashirodai, Kumatori-cho, Sennan-gun, Osaka 590-0496, Japan.
authors.forename: Shinji
authors.initials: S
authors.lastname: Yamamoto
authors.affiliation: Graduate School of Human and Environmental Studies, Kyoto University, Yoshida-nihonmatsu-cho, Sakyo-ku, Kyoto 606-8501, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Aihara
authors.affiliation: Center for Information and Neural Networks (CiNet), National Institute of Information and Communications Technology, 1-4 Yamadaoka, Suita, Osaka 565-0871, Japan; The Japan Society for the Promotion of Science, 5-3-1 Kojimachi, Chiyoda-ku, Tokyo 102-0083, Japan. Electronic address: s.uehara@nict.go.jp.
authors.forename: Shintaro
authors.initials: S
authors.lastname: Uehara
mesh_terms: D000328:Adult; D005260:Female; D007839:Functional Laterality; D006225:Hand / Q000502:physiology*; D006801:Humans; D007100:Imitative Behavior; D008297:Male; D009068:Movement; D011597:Psychomotor Performance; D011930:Reaction Time; D055815:Young Adult
keywords: Handedness; Mirror property; Mirror system; Motor imitation; Sensorimotor associative experience