New paper: Methodological challenges and solutions in auditory fMRI

Fresh off the Frontiers press, my review paper on auditory fMRI methods. There are a number of other papers on this topic, but most are more than a decade old. My goal in this paper was to give a contemporary overview of the current state of auditory fMRI, and emphasize a few points that sometimes fall by the wayside. Scanner noise is often seen as a methodological issue (and a nuisance)—and understandably so—but it's one that can drastically impact our interpretation of results, particularly for auditory fMRI studies.

One key point is that acoustic scanner noise can affect neural activity through multiple pathways. Typically the most focus is placed on audibility (can subjects hear the stimuli?), followed by acknowledging a possible reduction in sensitivity in auditory regions of the brain. However, acoustic noise can also change the cognitive processes required for tasks such as speech perception. Behaviorally there is an extensive literature showing that speech perception in quiet differs from speech perception in noise; the same is true in the scanner environment. Although we may not be able to provide optimal acoustic conditions inside a scanner, at a minimum it is useful to consider the possible impact of the acoustic challenge on observed neural responses. To me this continues to be an important point when interpreting auditory fMRI studies. I'm not convinced by the argument that because acoustic noise is present equally in all conditions, we don't have to worry about it—there are good reasons to think that acoustic challenge interacts with the cognitive systems engaged.

Another point that has long been around in the literature but frequently downplayed in practice is that scanner noise appears to impact other cognitive tasks, too—so it's not probably just auditory neuroscientists who should be paying attention to the issue of acoustic noise in the scanner.

On the solution side, at this point sparse imaging (aka "clustered volume acquisition") is fairly well-known. I also emphasize the benefits ISSS (Schwarzbauer et al, 2006), which is a more recent approach to auditory fMRI. ISSS allows improved temporal resolution while still presenting stimuli in relative quiet, although because it produces a discontinuous timeseries of images, some care needs to be taken during analysis.

It's clear that if we care about auditory processing, scanner noise will always be a challenge. However, I'm optimistic that with some increased attention to the issue and striving to understand the effects of scanner noise rather than ignore them, things will only get better. To quote the last line of the paper: "It is an exciting time for auditory neuroscience, and continuing technical and methodological advances suggest an even brighter (though hopefully quieter) future."

[As a side note I'm also happy to publish in the "Brain Imaging Methods" section of Frontiers. I wish it had it's own title, but it's subsumed in the Frontiers in Neuroscience journal for citation purposes.]



Peelle JE (2014) Methodological challenges and solutions in auditory functional magnetic resonance imaging. Frontiers in Neuroscience 8:253.

Schwarzbauer C, Davis MH, Rodd JM, Johnsrude I (2006) Interleaved silent steady state (ISSS) imaging: A new sparse imaging method applied to auditory fMRI. NeuroImage 29:774-782.