Time-course of the auditory BOLD response to scanner noise.
It is a concern for auditory fMRI studies that acoustic noise generated by the scanner produces an auditory response that can confound stimulus-induced activation. To establish how to minimize this problem, the present study mapped the time-course of the auditory response to a burst of acoustic scanner noise by employing a single-event method. Recorded bursts of scanner noise were interspersed with clustered-volume acquisitions at a range of stimulus-to-imaging delays to map the response with a temporal resolution of 1 sec. There were strong responses (1.5% signal change) to scanner noise in primary and secondary auditory cortex. In both cortical areas, the mean response rose to a peak by 4-5 sec after stimulus onset and decayed after a further 5-8 sec. The time course indicates that noise contamination in auditory fMRI can be substantially reduced by using a 9-12-sec repetition time, thus maximizing the dynamic range available for displaying the response to acoustical stimuli of interest.
Hall
D A
DA
MRC Institute of Hearing Research, University Park, Nottingham, UK.
Summerfield
A Q
AQ
Gonçalves
M S
MS
Foster
J R
JR
Palmer
A R
AR
Bowtell
R W
RW
D000328:Adult; D016477:Artifacts; D001309:Auditory Threshold / Q000502:physiology*; D017352:Echo-Planar Imaging / Q000009:adverse effects* / Q000295:instrumentation; D006801:Humans; D007091:Image Processing, Computer-Assisted; D011930:Reaction Time; D015203:Reproducibility of Results