title: Accelerometer-based automatic voice onset detection in speech mapping with navigated repetitive transcranial magnetic stimulation.
abstract: BACKGROUND
  The use of navigated repetitive transcranial magnetic stimulation (rTMS) in mapping of speech-related brain areas has recently shown to be useful in preoperative workflow of epilepsy and tumor patients. However, substantial inter- and intraobserver variability and non-optimal replicability of the rTMS results have been reported, and a need for additional development of the methodology is recognized. In TMS motor cortex mappings the evoked responses can be quantitatively monitored by electromyographic recordings; however, no such easily available setup exists for speech mappings.
  
  
  METHODS
  We present an accelerometer-based setup for detection of vocalization-related larynx vibrations combined with an automatic routine for voice onset detection for rTMS speech mapping applying naming.
  
  
  CONCLUSIONS
  The results produced by the automatic routine were compared with the manually reviewed video-recordings.
  
  
  RESULTS
  The new method was applied in the routine navigated rTMS speech mapping for 12 consecutive patients during preoperative workup for epilepsy or tumor surgery. The automatic routine correctly detected 96% of the voice onsets, resulting in 96% sensitivity and 71% specificity. Majority (63%) of the misdetections were related to visible throat movements, extra voices before the response, or delayed naming of the previous stimuli. The no-response errors were correctly detected in 88% of events.
  
  
  CONCLUSIONS
  The proposed setup for automatic detection of voice onsets provides quantitative additional data for analysis of the rTMS-induced speech response modifications. The objectively defined speech response latencies increase the repeatability, reliability and stratification of the rTMS results.
authors.affiliation: BioMag Laboratory, HUS Medical Imaging Center, University of Helsinki and Helsinki University Hospital, P.O. Box 340, FI-00029 HUS, Helsinki, Finland; Department of Physics, University of Helsinki, P.O. Box 64, FI-00014 University of Helsinki, Helsinki, Finland. Electronic address: anne-mari.vitikainen@hus.fi.
authors.forename: Anne-Mari
authors.initials: AM
authors.lastname: Vitikainen
authors.affiliation: BioMag Laboratory, HUS Medical Imaging Center, University of Helsinki and Helsinki University Hospital, P.O. Box 340, FI-00029 HUS, Helsinki, Finland. Electronic address: elina.makela@aalto.fi.
authors.forename: Elina
authors.initials: E
authors.lastname: Mäkelä
authors.affiliation: BioMag Laboratory, HUS Medical Imaging Center, University of Helsinki and Helsinki University Hospital, P.O. Box 340, FI-00029 HUS, Helsinki, Finland; Neuroscience Center, University of Helsinki, P.O. Box 56, FI-00014 University of Helsinki, Helsinki, Finland. Electronic address: pantelis.lioumis@helsinki.fi.
authors.forename: Pantelis
authors.initials: P
authors.lastname: Lioumis
authors.affiliation: Department of Neuroscience and Biomedical Engineering, Aalto University School of Science, P.O. Box 15100, FI-00076 Aalto, Espoo, Finland; Aalto NeuroImaging, Aalto University School of Science, P.O. Box 15100, FI-00076 Aalto, Espoo, Finland. Electronic address: veikko.jousmaki@aalto.fi.
authors.forename: Veikko
authors.initials: V
authors.lastname: Jousmäki
authors.affiliation: BioMag Laboratory, HUS Medical Imaging Center, University of Helsinki and Helsinki University Hospital, P.O. Box 340, FI-00029 HUS, Helsinki, Finland. Electronic address: jyrki.makela@hus.fi.
authors.forename: Jyrki P
authors.initials: JP
authors.lastname: Mäkelä
mesh_terms: D061725:Accelerometry; D000293:Adolescent; D000328:Adult; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D001932:Brain Neoplasms / Q000473:pathology; D002648:Child; D004827:Epilepsy / Q000473:pathology; D019054:Evoked Potentials, Motor / Q000502:physiology; D005260:Female; D007839:Functional Laterality; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007802:Language; D008279:Magnetic Resonance Imaging; D008297:Male; D038361:Neuronavigation; D011930:Reaction Time / Q000502:physiology; D017603:Signal Detection, Psychological; D013060:Speech / Q000502:physiology*; D050781:Transcranial Magnetic Stimulation; D014831:Voice; D055815:Young Adult
keywords: Navigated TMS (nTMS); Object naming; Presurgical planning; Speech mapping