TY - JOUR
T1 - BOLD correlates of trial-by-trial reaction time variability in gray and white matter
T2 - A multi-study fMRI analysis
AU - Yarkoni, Tal
AU - Barch, Deanna M.
AU - Gray, Jeremy R.
AU - Conturo, Thomas E.
AU - Braver, Todd S.
PY - 2009/1/23
Y1 - 2009/1/23
N2 - Background: Reaction time (RT) is one of the most widely used measures of performance in experimental psychology, yet relatively few fMRI studies have included trial-by-trial differences in RT as a predictor variable in their analyses. Using a multi-study approach, we investigated whether there are brain regions that show a general relationship between trial-by-trial RT variability and activation across a range of cognitive tasks. Methodology/Principal Findings: The relation between trial-by-trial differences in RT and brain activation was modeled in five different fMRI datasets spanning a range of experimental tasks and stimulus modalities. Three main findings were identified. First, in a widely distributed set of gray and white matter regions, activation was delayed on trials with long RTs relative to short RTs, suggesting delayed initiation of underlying physiological processes. Second, in lateral and medial frontal regions, activation showed a "time-on-task" effect, increasing linearly as a function of RT. Finally, RT variability reliably modulated the BOLD signal not only in gray matter but also in diffuse regions of white matter. Conclusions/Significance: The results highlight the importance of modeling trial-by-trial RT in fMRI analyses and raise the possibility that RT variability may provide a powerful probe for investigating the previously elusive white matter BOLD signal.
AB - Background: Reaction time (RT) is one of the most widely used measures of performance in experimental psychology, yet relatively few fMRI studies have included trial-by-trial differences in RT as a predictor variable in their analyses. Using a multi-study approach, we investigated whether there are brain regions that show a general relationship between trial-by-trial RT variability and activation across a range of cognitive tasks. Methodology/Principal Findings: The relation between trial-by-trial differences in RT and brain activation was modeled in five different fMRI datasets spanning a range of experimental tasks and stimulus modalities. Three main findings were identified. First, in a widely distributed set of gray and white matter regions, activation was delayed on trials with long RTs relative to short RTs, suggesting delayed initiation of underlying physiological processes. Second, in lateral and medial frontal regions, activation showed a "time-on-task" effect, increasing linearly as a function of RT. Finally, RT variability reliably modulated the BOLD signal not only in gray matter but also in diffuse regions of white matter. Conclusions/Significance: The results highlight the importance of modeling trial-by-trial RT in fMRI analyses and raise the possibility that RT variability may provide a powerful probe for investigating the previously elusive white matter BOLD signal.
UR - http://www.scopus.com/inward/record.url?scp=59249092918&partnerID=8YFLogxK
U2 - 10.1371/journal.pone.0004257
DO - 10.1371/journal.pone.0004257
M3 - Article
C2 - 19165335
AN - SCOPUS:59249092918
VL - 4
JO - PLoS ONE
JF - PLoS ONE
SN - 1932-6203
IS - 1
M1 - e4257
ER -