title: Influence of fMRI smoothing procedures on replicability of fine scale motor localization.
abstract: Recent publications analyzing the influence of spatial smoothing on fMRI brain activation results demonstrated that smoothing may artificially combine activations from adjacent though functionally and anatomically distinct brain regions and that activation from large draining vessels may be smoothed into neighboring neuronal tissue. To investigate whether functional localizations may be artificially shifted by the smoothing procedure we performed replicability measurements. Localization centers of motor hand activations achieved during different conditions (isolated hand movements and simultaneous hand and chin movements) were compared with respect to smoothing effects. The voxel with the highest probability to represent a true positive activation was localized with a non-smoothed and a standard 4 x 4 x 6 mm smoothed correlational data analysis technique. Results show an increase of motor center aberrations between measurements by about 100% due to data smoothing indicating a statistically significant decrease in localization replicability.
authors.affiliation: Study Group Clinical fMRI at the Departments of Neurology and Radiology, Medical University of Vienna, Währinger Gürtel 18-20, A-1090 Vienna, Austria.
authors.forename: Alexander
authors.initials: A
authors.lastname: Geissler
authors.forename: Rupert
authors.initials: R
authors.lastname: Lanzenberger
authors.forename: Markus
authors.initials: M
authors.lastname: Barth
authors.forename: Amir Reza
authors.initials: AR
authors.lastname: Tahamtan
authors.forename: Denny
authors.initials: D
authors.lastname: Milakara
authors.forename: Andreas
authors.initials: A
authors.lastname: Gartus
authors.forename: Roland
authors.initials: R
authors.lastname: Beisteiner
mesh_terms: D000328:Adult; D001931:Brain Mapping / Q000379:methods; D002680:Chin; D005260:Female; D007839:Functional Laterality; D006225:Hand; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D009044:Motor Cortex / Q000033:anatomy & histology* / Q000502:physiology*; D011336:Probability; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity