title: Functional imaging: heterogeneity in task strategy and functional anatomy and the case for individual analysis.
abstract: To learn more about the functional anatomy of language, the authors used [99mTc]HMPAO single photon emission computed tomography (SPECT) functional imaging to study nonword rhyming, lexical-semantics and syntax. The authors did not find any task-related differences in cerebral blood flow using region-by-region analysis of variance. This led them to examine individual subject's task-related patterns of cerebral blood flow. This analysis revealed regions of interest with little or no change but also regions with changes as great as 30%. There was marked subject-to-subject variability in the pattern of blood flow, which precluded statistically significant results using analysis of variance. An alternative analytic strategy based on numbers of subjects exceeding a minimum threshold task-related change in cerebral blood flow was tested and shows promise in identifying commonalities and differences in individual task-related blood flow patterns. The authors conclude that the complex and difficult to interpret pattern of blood flow changes observed in this study reflect in considerable part the combined effects of variability in task strategy, owing in part to insufficiently constrained task performance, and variability in functional anatomy. The authors also tested the differences in results achieved with simple normalization and analysis of covariance approaches and found them to be insignificant.
authors.affiliation: Geriatric Research, Education and Clinical Center, Department of Neurology, University of Florida College of Medicine, Gainesville, USA.
authors.forename: S E
authors.initials: SE
authors.lastname: Nadeau
authors.forename: D J
authors.initials: DJ
authors.lastname: Williamson
authors.forename: B
authors.initials: B
authors.lastname: Crosson
authors.forename: L J
authors.initials: LJ
authors.lastname: Gonzalez Rothi
authors.forename: K M
authors.initials: KM
authors.lastname: Heilman
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001783:Blood Flow Velocity; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000098:blood supply / Q000000981:diagnostic imaging*; D002560:Cerebrovascular Circulation; D003071:Cognition / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007802:Language; D008279:Magnetic Resonance Imaging; D008297:Male; D008606:Mental Processes; D012016:Reference Values; D019690:Technetium Tc 99m Exametazime; D015899:Tomography, Emission-Computed, Single-Photon
chemical_list: D019690:Technetium Tc 99m Exametazime