title: Detecting change in BOLD signal between sessions for atlas-based anatomical ROIs.
abstract: An algorithm using pre-defined regions of interest (ROIs) to detect differences between sessions in Blood Oxygen-Level Dependent (BOLD) signal is proposed and results from a reproducibility study are reported here. It is important to know whether tests for change have the desired statistical properties, e.g., low variability between sessions and unbiased false-positive rates, under null conditions so one is confident in any conclusions based on the metric and test used. This study examined three cognitive tasks: Stroop, response inhibition, Sternberg digits, and a visually-cued finger tapping task, in 20 healthy subjects. Each subject had two fMRI sessions, one week apart. A series of ROI summaries was constructed by choosing different proportions of voxels from the ROI and calculating the mean of t values for the selected voxels. The choice of voxels was based on the magnitude of the t values, selecting the maximum value, then the top 1%, and so on until all voxels in the ROI were included. No ROIs were found to have significant differences between sessions based on paired comparison t tests. Generally, the observed false-positive rates were near the expected rates for all summaries and tasks, although the Sternberg and Response Inhibition tasks did have higher false-positive rates when alpha>/= 0.1 for some ROI summaries. This study indicates results are reproducible and also have the desired statistical properties under null conditions.
authors.affiliation: Pfizer Inc, Ann Arbor, MI, USA. robert.j.buck@gmail.com
authors.forename: Robert
authors.initials: R
authors.lastname: Buck
authors.forename: Harsh
authors.initials: H
authors.lastname: Singhal
authors.forename: Jagriti
authors.initials: J
authors.lastname: Arora
authors.forename: Heidi
authors.initials: H
authors.lastname: Schlitt
authors.forename: R Todd
authors.initials: RT
authors.lastname: Constable
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000465:Algorithms; D016477:Artifacts; D001921:Brain / Q000033:anatomy & histology*; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010100:Oxygen / Q000097:blood*; D011597:Psychomotor Performance / Q000502:physiology; D015203:Reproducibility of Results
chemical_list: D010100:Oxygen