Are Brain Functions Really Additive?

Although Positron Emission Tomography (PET) and functional magnetic resonance imaging (fMRI) studies commonly subtract data obtained during two or more experimental conditions to decompose a complex task, there have been few opportunities to evaluate this approach directly. In the present study, PET...

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Bibliographic Details
Published in:NeuroImage (Orlando, Fla.) Fla.), 1999-05, Vol.9 (5), p.490-496
Main Authors: Sidtis, John J., Strother, Stephen C., Anderson, Jon R., Rottenberg, David A.
Format: Article
Language:English
Subjects:
Adult
Basal Ganglia - diagnostic imaging
Basal Ganglia - physiology
Brain - diagnostic imaging
Brain - physiology
Brain Mapping
Decomposition
Female
Functional magnetic resonance imaging
Handedness
Humans
Male
Middle Aged
Neuroimaging
Positron emission tomography
Reproducibility of Results
Scanning
Speech Production Measurement
Subtraction Technique
Tomography, Emission-Computed
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Summary:Although Positron Emission Tomography (PET) and functional magnetic resonance imaging (fMRI) studies commonly subtract data obtained during two or more experimental conditions to decompose a complex task, there have been few opportunities to evaluate this approach directly. In the present study, PET was used to study three motor speech tasks selected such that two were constituent components of the third, making possible a direct examination of decomposition by subtraction. In Experiment 1, a group of 13 right-handed normal volunteers participated in three activation studies: syllable repetition; phonation; and repetitive lip closure. A scanning session was devoted to a single task, repeated four times. In Experiment 2, six of the original subjects performed the same three activation studies during a single scanning session. Whether tasks were studied in separate scanning sessions or combined within a single session, the results of decomposition by compound subtraction differed significantly from the results obtained when individual tasks were compared to a simple baseline condition. These data failed to demonstrate task additivity, a necessary property if decomposition by subtraction is to provide an accurate characterization of the brain activity accompanying complex behavior.
ISSN:1053-8119
1095-9572
DOI:10.1006/nimg.1999.0423