title: The Measurement of Language Lateralization with Functional Transcranial Doppler and Functional MRI: A Critical Evaluation.
abstract: Cerebral language lateralization can be assessed in several ways. In healthy subjects, functional MRI (fMRI) during performance of a language task has evolved to be the most frequently applied method. Functional transcranial Doppler (fTCD) may provide a valid alternative, but has been used rarely. Both techniques have their own strengths and weaknesses and as a result may be applied in different fields of research. Until now, only one relatively small study (n = 13) investigated the correlation between lateralization indices (LIs) measured by fTCD and fMRI and showed a remarkably high correlation. To further evaluate the correlation between LIs measured with fTCD and fMRI, we compared LIs of 22 healthy subjects (12 left- and 10 right-handed) using the same word generation paradigm for the fTCD as for the fMRI experiment. LIs measured with fTCD were highly but imperfectly correlated with LIs measured with fMRI (Spearman's rho = 0.75, p < 0.001). The imperfectness of the correlation can partially be explained by methodological restrictions of fMRI as well as fTCD. Our results suggest that fTCD can be a valid alternative for fMRI to measure lateralization, particularly when costs or mobility are important factors in the study design.
authors.affiliation: Department of Psychiatry, Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht Utrecht, Netherlands.
authors.forename: Metten
authors.initials: M
authors.lastname: Somers
authors.forename: Sebastiaan F
authors.initials: SF
authors.lastname: Neggers
authors.forename: Kelly M
authors.initials: KM
authors.lastname: Diederen
authors.forename: Marco P
authors.initials: MP
authors.lastname: Boks
authors.forename: René S
authors.initials: RS
authors.lastname: Kahn
authors.forename: Iris E
authors.initials: IE
authors.lastname: Sommer