Acoustic noise and functional magnetic resonance imaging: Current strategies and future prospects

Abstract

Functional magnetic resonance imaging (fMRI) has become the method of choice for studying the neural correlates of cognitive tasks. Nevertheless, the scanner produces acoustic noise during the image acquisition process, which is a problem in the study of auditory pathway and language generally. The scanner acoustic noise not only produces activation in brain regions involved in auditory processing, but also interferes with the stimulus presentation. Several strategies can be used to address this problem, including modifications of hardware and software. Although reduction of the source of the acoustic noise would be ideal, substantial hardware modifications to the current base of installed MRI systems would be required. Therefore, the most common strategy employed to minimize the problem involves software modifications. In this work we consider three main types of acquisitions: compressed, partially silent, and silent. For each implementation, paradigms using block and event-related designs are assessed. We also provide new data, using a silent event-related (SER) design, which demonstrate higher blood oxygen level-dependent (BOLD) response to a simple auditory cue when compared to a conventional image acquisition.

Lateralization of functional magnetic resonance imaging (fMRI) activation in the auditory pathway of patients with lateralized tinnitus

“…Some attenuation (up to 30 dB) of the background scanner noise can be achieved by using special padded headphones, as used in our study, through which the stimuli are delivered. Silent fMRI techniques, such as the BURST sequence, are very effective in reducing acoustic noise [36], but most tend to be too slow for fMRI studies [37]. Longer noise-free periods-known as sparse temporal sampling-during acquisition are also useful in reducing the amount of scanner-generated noise and have been shown to improve fMRI activation of the auditory system, but the amount of information acquired is usually decreased and acquisition times are long [33,35,38].…”

Auditory context effects in picture naming investigated with event-related fMRI

“…These discrepant results may be due to a number of methodological issues associated with the study design, including the early SOA used, subjective (i.e., manual) determination of response latencies, and use of a conventional continuous fMRI acquisition. Gradient noise is well known to activate temporal lobe regions involved in auditory processing and to interfere with auditory stimulus presentation (see Amaro et al, 2002).…”

Auditory processing abnormalities in schizotypal personality disorder: An fMRI experiment using tones of deviant pitch and duration

“…We note that a silent event-related design, in which the scanner would not scan during stimuli presentation, would more fully remove the confound of interference from scanner noise. Unfortunately, such a design would also significantly increase the scanning time (a mean of 14 s between stimuli as proposed by Amaro et al, 2002). In addition, one cannot modulate scanner frequency or pitch, thus limiting the exploration of differential pitch discrimination in SPD subjects.…”