title: How does spatial extent of fMRI datasets affect independent component analysis decomposition?
abstract: Spatial independent component analysis (sICA) of functional magnetic resonance imaging (fMRI) time series can generate meaningful activation maps and associated descriptive signals, which are useful to evaluate datasets of the entire brain or selected portions of it. Besides computational implications, variations in the input dataset combined with the multivariate nature of ICA may lead to different spatial or temporal readouts of brain activation phenomena. By reducing and increasing a volume of interest (VOI), we applied sICA to different datasets from real activation experiments with multislice acquisition and single or multiple sensory-motor task-induced blood oxygenation level-dependent (BOLD) signal sources with different spatial and temporal structure. Using receiver operating characteristics (ROC) methodology for accuracy evaluation and multiple regression analysis as benchmark, we compared sICA decompositions of reduced and increased VOI fMRI time-series containing auditory, motor and hemifield visual activation occurring separately or simultaneously in time. Both approaches yielded valid results; however, the results of the increased VOI approach were spatially more accurate compared to the results of the decreased VOI approach. This is consistent with the capability of sICA to take advantage of extended samples of statistical observations and suggests that sICA is more powerful with extended rather than reduced VOI datasets to delineate brain activity.
authors.affiliation: Second Division of Neurology, Second University of Naples, Naples, Italy. adrianaaragri@libero.it
authors.forename: Adriana
authors.initials: A
authors.lastname: Aragri
authors.forename: Tommaso
authors.initials: T
authors.lastname: Scarabino
authors.forename: Erich
authors.initials: E
authors.lastname: Seifritz
authors.forename: Silvia
authors.initials: S
authors.lastname: Comani
authors.forename: Sossio
authors.initials: S
authors.lastname: Cirillo
authors.forename: Gioacchino
authors.initials: G
authors.lastname: Tedeschi
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Esposito
authors.forename: Francesco
authors.initials: F
authors.lastname: Di Salle
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D010775:Photic Stimulation; D025341:Principal Component Analysis / Q000379:methods; D012372:ROC Curve; D012680:Sensitivity and Specificity