title: Non-invasive assessment of hemispheric language dominance by optical topography during a brief passive listening test: a pilot study.
abstract: BACKGROUND
  The Wada test is usually used for pre-surgical assessment of language lateralization. Considering its invasiveness and risk of complications, alternative methods have been proposed but they are not always applicable to non-cooperative patients. In this study we explored the possibility of using optical topography (OT)--a multichannel near-infrared system--for non-invasive assessment of hemispheric language dominance during passive listening.
  
  
  METHODS
  Cortical activity was monitored in a sample of healthy, adult Italian native speakers, all right-handed. We assessed changes in oxy-haemoglobin concentration in temporal, parietal and posterior frontal lobes during a passive listening of bi-syllabic words and vowel-consonant-vowel syllables lasting less then 3 minutes. Activated channels were identified by t tests.
  
  
  RESULTS
  Left hemisphere showed significant activity only during the passive listening of bi-syllabic words. Specifically, the superior temporal gyrus, the supramarginal gyrus and the posterior inferior parietal lobe were activated.
  
  
  CONCLUSIONS
  During passive listening of bi-syllabic words, right handed healthy adults showed a significant activation in areas already known to be involved in speech comprehension. Although more research is needed, OT proved to be a promising alternative to the Wada test for non-invasive assessment of hemispheric language lateralization, even if using a particularly brief trial, which has been designed for future applications with non-cooperative subjects.
authors: Department of Medical, Surgical and Health Sciences, University of Trieste, Trieste, Italy. stefbemb@libero.it
authors: Stefano
authors: S
authors: Bembich
authors: Sergio
authors: S
authors: Demarini
authors: Andrea
authors: A
authors: Clarici
authors: Stefano
authors: S
authors: Massaccesi
authors: Domenico Loenardo
authors: DL
authors: Grasso
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D054022:Cerebrum / Q000502:physiology*; D019937:Diagnostic Techniques and Procedures; D004292:Dominance, Cerebral / Q000502:physiology*; D005260:Female; D006801:Humans; D007802:Language; D008297:Male; D008875:Middle Aged; D010108:Oxyhemoglobins / Q000378:metabolism; D010865:Pilot Projects; D019265:Spectroscopy, Near-Infrared / Q000379:methods*
chemical_list: D010108:Oxyhemoglobins