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Cortical activation response to acoustic echo planar scanner noise
J L Ulmer1, B B Biswal, F Z Yetkin
1Department of Radiology, Medical College of Wisconsin, Milwaukee, USA.
Journal of Computer Assisted Tomography
|February 4, 1998
Summary
Functional MRI (fMRI) studies show scanner noise activates auditory and language cortex. While primary auditory cortex activation is consistent, surrounding areas show variable responses across individuals but are stable within subjects.
Area of Science:
- Neuroimaging
- Auditory Neuroscience
- Cognitive Neuroscience
Background:
- Functional magnetic resonance imaging (fMRI) is a powerful tool for studying brain activity.
- The acoustic noise generated by fMRI scanners can potentially interfere with or activate auditory and language processing regions.
- Understanding the extent and consistency of brain activation by scanner noise is crucial for interpreting fMRI results.
Purpose of the Study:
- To investigate the distribution of auditory and language cortex activation in response to acoustic echo planar scanner noise using fMRI.
- To assess the consistency of cortical activation to scanner noise stimulus across multiple task iterations.
Main Methods:
- Six healthy adults underwent fMRI while exposed to acoustic scanner noise and spoken text via earphones at equivalent intensities.
- Nine additional subjects were tested with scanner noise across five successive task iterations to evaluate activation consistency.
- Cortical activation was analyzed in 10 subregions of the auditory and language systems using cross-correlation analysis.
Main Results:
- All subjects showed cortical activation in the primary auditory cortex (transverse temporal gyrus) in response to scanner noise.
- Activation in auditory association and language cortex was variable across subjects but consistent within individuals across repeated noise exposures.
- Spoken text consistently activated primary and association auditory cortex bilaterally, and language cortex in some cases, with greater activation than scanner noise.
Conclusions:
- Acoustic echo planar scanner noise can activate bilateral auditory and language cortex, with variable activation extent outside the primary auditory cortex.
- Individual subject activation patterns to scanner noise were consistent across multiple repetitions.
- This highlights the importance of considering scanner noise as a potential confound in fMRI studies of auditory and language processing.