title: The effect of swallowing treatments on corticobulbar excitability: a review of transcranial magnetic stimulation induced motor evoked potentials.
abstract: Transcranial magnetic stimulation (TMS) has been used extensively as a method of investigating the corticomotor physiology of many motor tasks, including healthy and disordered swallowing. Changes in excitability of cortical projections to various swallowing muscles have been documented in response to treatments with TMS induced motor evoked potentials (MEPs). These studies have provided valuable insight into CNS response to swallowing impairment, and more importantly, the adaptations associated with functional recovery. However, unique obstacles are presented when investigating corticobulbar neurophysiology associated with the complex task of swallowing. Stringent methodological control and supplementary outcome measures are required to ensure robust and clinically applicable findings. This article offers a tutorial for the researcher who may be considering the use of TMS for investigating changes in cortical excitability associated with various swallowing paradigms. Included is a review of the mechanisms of TMS and what can be measured with this technique, a summary of existing research using MEPs to investigate swallowing, a review of methodological factors that may influence outcomes, and proposed directions for new areas of research.
authors.affiliation: New Zealand Brain Research Institute, 66 Stewart Street, Christchurch, New Zealand; Department of Communication Disorders, University of Canterbury, Private Bag 4800, Christchurch, New Zealand. Electronic address: pmacrae1@icloud.com.
authors.forename: Phoebe R
authors.initials: PR
authors.lastname: Macrae
authors.affiliation: New Zealand Brain Research Institute, 66 Stewart Street, Christchurch, New Zealand; Department of Communication Disorders, University of Canterbury, Private Bag 4800, Christchurch, New Zealand; Department of Medicine, University of Otago, Private Bag 4710, Christchurch, New Zealand; Department of Medical Physics and Bioengineering, Canterbury District Health Board, Private Bag 4710, Christchurch, New Zealand. Electronic address: richard.jones@nzbri.org.
authors.forename: Richard D
authors.initials: RD
authors.lastname: Jones
authors.affiliation: New Zealand Brain Research Institute, 66 Stewart Street, Christchurch, New Zealand; Department of Communication Disorders, University of Canterbury, Private Bag 4800, Christchurch, New Zealand. Electronic address: maggie-lee.huckabee@canterbury.ac.nz.
authors.forename: Maggie-Lee
authors.initials: ML
authors.lastname: Huckabee
mesh_terms: D000818:Animals; D001921:Brain / Q000502:physiology / Q000503:physiopathology; D003679:Deglutition / Q000502:physiology*; D003680:Deglutition Disorders / Q000503:physiopathology / Q000628:therapy*; D004576:Electromyography / Q000379:methods; D019054:Evoked Potentials, Motor; D006801:Humans; D009132:Muscles / Q000502:physiology / Q000503:physiopathology; D011712:Pyramidal Tracts / Q000502:physiology* / Q000503:physiopathology; D050781:Transcranial Magnetic Stimulation
keywords: Dysphagia; Motor evoked potentials; Neurophysiology; Swallowing; Transcranial magnetic stimulation