False activation in the brain ventricles related to task-correlated breathing in fMRI speech and motor paradigms.
OBJECTIVE
We demonstrate, and show how to eliminate, a task-correlated breathing activation artefact created while performing exercise tasks during a gap in functional magnetic resonance imaging (fMRI).


METHODS
Two studies are presented. The first was intended to isolate a reliable fMRI paradigm for intense handgrip contractions. A gapped acquisition was used to reduce motion artefact, where the contraction was performed during a gap, and image acquisition was between contractions. The second study involved naming regular words (REGs) and nonwords (NWs), where a gap is required for the analysis of participants' overt speech.


RESULTS
For study 1, brain ventricle activation was present when breathing responses were task-correlated, and was only eliminated by removing the gap from the sequence. For study 2, NWs were associated with activation artefact in the ventricles, and slower reaction time (RT), reflecting a strategy whereby breathing falls in synchrony with image acquisition. REGs showed the expected RT distribution and frequency effect (reflecting lexical access), with no ventricle activation, and consequently no synchrony with image acquisition.


CONCLUSIONS
The gapped paradigm increased the likelihood of breathing correlated T2* signal changes in brain ventricles. FMRI researchers should examine the brain ventricles for activation artefact as they are likely associated with false activations in other brain regions.
Farthing
Jonathan P
JP
College of Kinesiology, University of Saskatchewan, 87 Campus Drive, Saskatoon, SK, Canada, S7N 5B2. jon.farthing@usask.ca
Cummine
Jacqueline
J
Borowsky
Ron
R
Chilibeck
Philip D
PD
Binsted
Gord
G
Sarty
Gordon E
GE
D000328:Adult; D016477:Artifacts; D001931:Brain Mapping / Q000379:methods; D002552:Cerebral Ventricles / Q000502:physiology*; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D009048:Motor Skills; D015203:Reproducibility of Results; D015656:Respiratory Mechanics; D012680:Sensitivity and Specificity; D013060:Speech / Q000502:physiology*; D013647:Task Performance and Analysis