The use of fMRI to detect neural responses to cognitive interference and planning: evidence for a contribution of task related changes in heart rate?
fMRI signals during rest are strongly correlated with heart rate variations. These heart rate/fMRI associations may influence the results of brain activation studies, particularly if heart rate is affected by the task. To assess the contribution of task-related heart rate changes on fMRI brain activation related to executive processing, we co-registered the electrocardiogram with fMRI in 91 subjects during an interference task (color-word Stroop) and during a planning task (Tower of London; ToL). We found that both Stroop interference and ToL planning significantly increased heart rate in the scanner and confirmed significant main effects of heart rate regressors on the fMRI signals. Nevertheless, statistical contrasts that test for increased fMRI during Stroop interference and ToL planning were not significantly influenced by inclusion of heart rate regressors. We conclude therefore that fMRI changes associated with heart rate changes do not impact strongly on higher-order fMRI effects in these commonly used executive function tasks, but routinely adding a correction seems prudent.
Department of Biological Psychology, VU University, Amsterdam, The Netherlands; Neuroscience Campus Amsterdam (NCA), The Netherlands. Electronic address: d.vant.ent@vu.nl.
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van 't Ent
Department of Biological Psychology, VU University, Amsterdam, The Netherlands; Neuroscience Campus Amsterdam (NCA), The Netherlands.
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den Braber
Department of Physics and Medical Technology, VU medical center, Amsterdam, The Netherlands; Neuroscience Campus Amsterdam (NCA), The Netherlands.
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Rotgans
Department of Biological Psychology, VU University, Amsterdam, The Netherlands; Neuroscience Campus Amsterdam (NCA), The Netherlands.
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de Geus
Department of Physics and Medical Technology, VU medical center, Amsterdam, The Netherlands; Neuroscience Campus Amsterdam (NCA), The Netherlands.
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de Munck
D000328:Adult; D001921:Brain / Q000098:blood supply / Q000502:physiology*; D001931:Brain Mapping / Q000379:methods*; D003071:Cognition / Q000502:physiology*; D004562:Electrocardiography; D056344:Executive Function / Q000502:physiology*; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D009483:Neuropsychological Tests; D010100:Oxygen / Q000097:blood; D012042:Registries; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted; D057190:Stroop Test
D010100:Oxygen
Cognitive tasks; Confound; Heart rate; Stroop; ToL; fMRI