title: Excitability of hand motor areas during articulation of syllables.
abstract: It is known that articulating different syllables is linked to different grasp actions, e.g. [ti] is linked to precision grip, and [kɑ] to power grip. The aim of the present study was to test whether articulating or hearing these syllables would result in an increased activity in the representation of hand muscles involved in these two actions in a muscle-specific manner. To this end, we used transcranial magnetic stimulation (TMS) to investigate changes in the excitability of the left primary motor cortex (M1) innervating hand muscles while participants articulated or listened to meaningless syllables, listened to a metronome, or observed a fixation cross. The motor-evoked potentials of two hand muscles associated with either a precision or power grip exhibited significantly greater amplitudes during articulation than in passive listening, metronome, and fixation cross conditions. Moreover, these muscles exhibited similar patterns of excitability during articulation regardless of which syllable was articulated. The increased excitability of the left M1 hand area during articulation, but not during perception of the syllables, might be due to the cortico-cortical interaction between the motor representations of oral organs with the hand area.
authors.affiliation: Division of Cognitive and Neuropsychology, Institute of Behavioural Sciences, University of Helsinki, Siltavuorenpenger 1-5, 00014 University of Helsinki, Finland. Electronic address: naeem.komeilipoor@helsinki.fi.
authors.forename: Naeem
authors.initials: N
authors.lastname: Komeilipoor
authors.affiliation: Division of Cognitive and Neuropsychology, Institute of Behavioural Sciences, University of Helsinki, Siltavuorenpenger 1-5, 00014 University of Helsinki, Finland.
authors.forename: Mikko
authors.initials: M
authors.lastname: Tiainen
authors.affiliation: Division of Cognitive and Neuropsychology, Institute of Behavioural Sciences, University of Helsinki, Siltavuorenpenger 1-5, 00014 University of Helsinki, Finland.
authors.forename: Kaisa
authors.initials: K
authors.lastname: Tiippana
authors.affiliation: Phonetics and Speech Synthesis Research Group, Institute of Behavioural Sciences, University of Helsinki, Siltavuorenpenger 1-5, 00014 University of Helsinki, Finland.
authors.forename: Martti
authors.initials: M
authors.lastname: Vainio
authors.affiliation: Division of Cognitive and Neuropsychology, Institute of Behavioural Sciences, University of Helsinki, Siltavuorenpenger 1-5, 00014 University of Helsinki, Finland.
authors.forename: Lari
authors.initials: L
authors.lastname: Vainio
mesh_terms: D000328:Adult; D019054:Evoked Potentials, Motor; D005260:Female; D006225:Hand / Q000294:innervation*; D006801:Humans; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D018482:Muscle, Skeletal / Q000294:innervation*; D013067:Speech Perception; D050781:Transcranial Magnetic Stimulation; D014705:Verbal Behavior
keywords: Articulation; Motor cortex excitability; Syllable perception; Transcranial magnetic stimulation