Lying in a 3T MRI scanner induces neglect-like spatial attention bias.

Axel Lindner,Daniel Wiesen,Hans-Otto Karnath

doi:10.7554/elife.71076

Axel Lindner, Daniel Wiesen + Show 1 more

Open Access

https://doi.org/10.7554/elife.71076

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Journal: eLife	Publication Date: Sep 29, 2021
Citations: 6	License type: CC BY 4.0

Affiliation: University of Tübingen, University of South Carolina

Abstract

The static magnetic field of MRI scanners can induce a magneto-hydrodynamic stimulation of the vestibular organ (MVS). In common fMRI settings, this MVS effect leads to a vestibular ocular reflex (VOR). We asked whether - beyond inducing a VOR - putting a healthy subject in a 3T MRI scanner would also alter goal-directed spatial behavior, as is known from other types of vestibular stimulation. We investigated 17 healthy volunteers, all of which exhibited a rightward VOR inside the MRI-scanner as compared to outside-MRI conditions. More importantly, when probing the distribution of overt spatial attention inside the MRI using a visual search task, subjects scanned a region of space that was significantly shifted toward the right. An additional estimate of subjective straight-ahead orientation likewise exhibited a rightward shift. Hence, putting subjects in a 3T MRI-scanner elicits MVS-induced horizontal biases of spatial orienting and exploration, which closely mimic that of stroke patients with spatial neglect.

Highlights

2011 observed that healthy subjects who were exposed to the static magnetic field of 3T and 7T MRI scanners developed a persistent horizontal nystagmus in complete darkness
These studies have further corroborated the initial conclusion by Roberts et al, 2011 that the nystagmus is caused by Lorentz forces that result from the interaction of the static magnetic field of the scanner and ionic currents in the endolymph fluid of the subject’s labyrinth
Parts of our procedures resembled that of typical fMRI experiments: We placed our subjects with their back on the scanner table and their head rested inside a 20-channel head-coil

Summary

Introduction

Roberts et al, 2011 observed that healthy subjects who were exposed to the static magnetic field of 3T and 7T MRI scanners developed a persistent horizontal nystagmus in complete darkness Since this effect was replicated by various groups Mian et al, 2013; Boegle et al, 2016) and was shown to be present for standard fMRI settings at 1.5T and 3T (Boegle et al, 2016) These studies have further corroborated the initial conclusion by Roberts et al, 2011 that the nystagmus is caused by Lorentz forces that result from the interaction of the static magnetic field of the scanner and ionic currents in the endolymph fluid of the subject’s labyrinth (see Ward et al, 2019 for review). The VOR supports – together with the visually induced optokinetic reflex – the stabilization of the retinal image despite head-m otion (for review e.g. see Ilg, 1997; Angelaki and Cullen, 2008)

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