title: Auditory intensity processing: Effect of MRI background noise.
abstract: Studies on active auditory intensity discrimination in humans showed equivocal results regarding the lateralization of processing. Whereas experiments with a moderate background found evidence for right lateralized processing of intensity, functional magnetic resonance imaging (fMRI) studies with background scanner noise suggest more left lateralized processing. With the present fMRI study, we compared the task dependent lateralization of intensity processing between a conventional continuous echo planar imaging (EPI) sequence with a loud background scanner noise and a fast low-angle shot (FLASH) sequence with a soft background scanner noise. To determine the lateralization of the processing, we employed the contralateral noise procedure. Linearly frequency modulated (FM) tones were presented monaurally with and without contralateral noise. During both the EPI and the FLASH measurement, the left auditory cortex was more strongly involved than the right auditory cortex while participants categorized the intensity of FM tones. This was shown by a strong effect of the additional contralateral noise on the activity in the left auditory cortex. This means a massive reduction in background scanner noise still leads to a significant left lateralized effect. This suggests that the reversed lateralization in fMRI studies with loud background noise in contrast to studies with softer background cannot be fully explained by the MRI background noise.
authors.affiliation: Leibniz Institute for Neurobiology, Brenneckestr. 6, 39118 Magdeburg, Germany. Electronic address: nicole.angenstein@lin-magdeburg.de.
authors.forename: Nicole
authors.initials: N
authors.lastname: Angenstein
authors.affiliation: Leibniz Institute for Neurobiology, Brenneckestr. 6, 39118 Magdeburg, Germany.
authors.forename: Jörg
authors.initials: J
authors.lastname: Stadler
authors.affiliation: Leibniz Institute for Neurobiology, Brenneckestr. 6, 39118 Magdeburg, Germany.
authors.forename: André
authors.initials: A
authors.lastname: Brechmann
mesh_terms: D000161:Acoustic Stimulation; D000162:Acoustics; D000328:Adult; D016477:Artifacts; D001303:Auditory Cortex / Q000502:physiology*; D001306:Auditory Pathways / Q000502:physiology; D001307:Auditory Perception; D001309:Auditory Threshold; D001931:Brain Mapping / Q000009:adverse effects* / Q000295:instrumentation; D054022:Cerebrum / Q000502:physiology*; D004867:Equipment Design; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000009:adverse effects* / Q000295:instrumentation; D008297:Male; D009622:Noise / Q000009:adverse effects*; D011237:Predictive Value of Tests; D011930:Reaction Time; D015203:Reproducibility of Results; D013018:Sound Spectrography; D055815:Young Adult
keywords: Background noise; Categorization; Functional magnetic resonance imaging; Hemispheric specialization; Human auditory perception