title: Preparatory state and postural adjustment strategies for choice reaction step initiation.
abstract: A loud auditory stimulus (LAS) presented simultaneously with a visual imperative stimulus can reduce reaction time (RT) by automatically triggering a movement prepared in the brain and has been used to investigate a movement preparation. It is still under debate whether or not a response is prepared in advance in RT tasks involving choice responses. The purpose of the present study was to investigate the preparatory state of anticipatory postural adjustments (APAs) during a choice reaction step initiation. Thirteen young adults were asked to step forward in response to a visual imperative stimulus in two choice stepping conditions: (i) the responding side is not known and must be selected and (ii) the responding side is known but whether to initiate or inhibit a step response must be selected. LAS was presented randomly and simultaneously with the visual imperative stimulus. LAS significantly increased the occurrence rates of inappropriately initiated APAs while reducing the RTs of correct and incorrect trials in both task conditions, demonstrating that LAS triggered the prepared APA automatically. This observation suggests that APAs are prepared in advance and withheld from release until the appropriate timing during a choice reaction step initiation. The preparatory activity of APAs might be modulated by the inhibitory activity required by the choice tasks. The preparation strategy may be chosen for fast responses and is judged most suitable to comply with the tasks because inappropriately initiated APAs can be corrected without making complete stepping errors.
authors.affiliation: Department of Physical Therapy, Nagoya University Graduate School of Medicine, Aichi 461-8673, Japan.
authors.forename: Tatsunori
authors.initials: T
authors.lastname: Watanabe
authors.affiliation: Department of Physical Therapy, Nagoya University Graduate School of Medicine, Aichi 461-8673, Japan.
authors.forename: Kazuto
authors.initials: K
authors.lastname: Ishida
authors.affiliation: Faculty of Rehabilitation, Fujita Health University School of Health Sciences, Aichi 470-1192, Japan.
authors.forename: Shigeo
authors.initials: S
authors.lastname: Tanabe
authors.affiliation: Department of Physical Therapy, Nagoya University Graduate School of Medicine, Aichi 461-8673, Japan. Electronic address: nojima@met.nagoya-u.ac.jp.
authors.forename: Ippei
authors.initials: I
authors.lastname: Nojima
mesh_terms: D000161:Acoustic Stimulation; D059031:Anticipation, Psychological / Q000502:physiology; D002755:Choice Behavior / Q000502:physiology; D003220:Conflict, Psychological; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D009043:Motor Activity / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology; D010775:Photic Stimulation; D011187:Posture / Q000502:physiology; D011581:Psychological Tests; D011930:Reaction Time; D013216:Reflex, Startle / Q000502:physiology; D016138:Walking / Q000502:physiology; D055815:Young Adult
keywords: anticipatory postural adjustments; choice stepping; gait initiation; loud auditory stimulus; preparation