Lying in a 3T MRI Scanner Induces Neglect-Like Spatial Attention Bias

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 towards the right. An additional estimate of subjective straight-ahead orientation likewise exhibited an MVC-induced rightward shift. Hence, putting a subject in a 3T MRI-scanner induces a bias of spatial attention, which closely mimics that of stroke patients with spatial neglect.