title: Preparation and execution of teeth clenching and foot muscle contraction influence on corticospinal hand-muscle excitability.
abstract: Contraction of a muscle modulates not only the corticospinal excitability (CSE) of the contracting muscle but also that of different muscles. We investigated to what extent the CSE of a hand muscle is modulated during preparation and execution of teeth clenching and ipsilateral foot dorsiflexion either separately or in combination. Hand-muscle CSE was estimated based on motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation (TMS) and recorded from the first dorsal interosseous (FDI) muscle. We found higher excitability during both preparation and execution of all the motor tasks than during mere observation of a fixation cross. As expected, the excitability was greater during the execution phase than the preparation one. Furthermore, both execution and preparation of combined motor tasks led to higher excitability than individual tasks. These results extend our current understanding of the neural interactions underlying simultaneous contraction of muscles in different body parts.
authors.affiliation: Division of Cognitive and Neuropsychology, Institute of Behavioural Sciences, University of Helsinki, Finland.
authors.forename: Naeem
authors.initials: N
authors.lastname: Komeilipoor
authors.affiliation: Department of Neuroscience and Biomedical Engineering, Aalto University School of Science, Espoo, Finland.
authors.forename: Risto J
authors.initials: RJ
authors.lastname: Ilmoniemi
authors.affiliation: Division of Cognitive and Neuropsychology, Institute of Behavioural Sciences, 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, Finland.|Department of Modern Languages, 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, Finland.
authors.forename: Mikko
authors.initials: M
authors.lastname: Tiainen
authors.affiliation: Division of Cognitive and Neuropsychology, Institute of Behavioural Sciences, University of Helsinki, Finland.
authors.forename: Lari
authors.initials: L
authors.lastname: Vainio
mesh_terms: D019054:Evoked Potentials, Motor / Q000502:physiology; D005260:Female; D005528:Foot / Q000502:physiology*; D006225:Hand / Q000502:physiology*; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D011712:Pyramidal Tracts / Q000502:physiology*; D014070:Tooth / Q000502:physiology*; D055815:Young Adult