Effect of scanner acoustic background noise on strict resting-state fMRI

Abstract

Functional MRI (fMRI) resting-state experiments are aimed at identifying brain networks that support basal brain function. Although most investigators consider a ‘resting-state’ fMRI experiment with no specific external stimulation, subjects are unavoidably under heavy acoustic noise produced by the equipment. In the present study, we evaluated the influence of auditory input on the resting-state networks (RSNs). Twenty-two healthy subjects were scanned using two similar echo-planar imaging sequences in the same 3T MRI scanner: a default pulse sequence and a reduced “silent” pulse sequence. Experimental sessions consisted of two consecutive 7-min runs with noise conditions (default or silent) counterbalanced across subjects. A self-organizing group independent component analysis was applied to fMRI data in order to recognize the RSNs. The insula, left middle frontal gyrus and right precentral and left inferior parietal lobules showed significant differences in the voxel-wise comparison between RSNs depending on noise condition. In the presence of low-level noise, these areas Granger-cause oscillations in RSNs with cognitive implications (dorsal attention and entorhinal), while during high noise acquisition, these connectivities are reduced or inverted. Applying low noise MR acquisitions in research may allow the detection of subtle differences of the RSNs, with implications in experimental planning for resting-state studies, data analysis, and ergonomic factors.

Age‐related change of auditory functional connectivity in Human Connectome Project data and tinnitus patients

“…The different MRI scanners between HCP subjects and tinnitus patients might add variability, but the results are comparable, because we evaluated relatively large amount of signals in auditory ROIs. The high‐level noise produced by the MRI scanner can induce an overload the posterior cingulate cortex . To reduce the possible influence by high noise levels, the subjects were physically attenuated about 40 dB of noise by using earmuffs and earplugs .…”

“…The highlevel noise produced by the MRI scanner can induce an overload the posterior cingulate cortex. 23 To reduce the possible influence by high noise levels, the subjects were physically attenuated about 40 dB of noise by using earmuffs and earplugs. 24 Third, the number of sample size is small and statistically underpowered.…”

Applicability of the Sparse Temporal Acquisition Technique in Resting-State Brain Network Analysis

“…To date, 2 reported studies evaluated the SBN effect on the resting state. Rondioni et al 12 used a "silent" EPI sequence, which allowed reduction of SBN by only approximately 12 dB. Although quieter than the original EPI SBN level, this does not seem to provide an adequately "silent" environment suitable for auditory studies.…”

Abnormal spontaneous neural activity of auditory cortex and auditory pathway in tinnitus: a resting-state fMRI study

“…Therefore, future studies must analyze a larger subgroup of tinnitus cases and include lateral tinnitus, hearing impairment grading, age grouping, and multiple etiologies, across multiple centers. Moreover, we cannot completely eliminate the substantial acoustic noise produced during the fMRI procedure with ear plugs and MRI noise-cancelling headphones, which might affect baseline neural activity (Rondinoni, et al,2013). Finally, the neural activity of special regions in the auditory system might be modulated by attention in consciousness (Jäncke, et al,1999;Martinez-Granados, et al,2014;Ghazaleh, et al,2017) and we cannot be sure that all subjects followed all requirements, including keeping eyes closed, staying relaxed, and avoiding any thinking.…”