Head movement in static magnetic stray field temporarily affects concentration, orientation
FRIDAY, Aug. 31 (HealthDay News) -- Exposure to movement-induced time-varying magnetic fields within a static magnetic stray field of a magnetic resonance imaging (MRI) scanner, which is always present even if no imaging is taking place, temporarily impairs attention, concentration, and visuospatial orientation, according to a study published online Aug. 29 in Occupational & Environmental Medicine.
Lotte E. van Nierop, from Utrecht University in the Netherlands, and colleagues exposed 31 healthy volunteers to a static magnetic stray field from a 7 Tesla MRI scanner at 0 Tesla (sham), 0.5 Tesla (low), and 1.0 Tesla (high). The volunteers made standardized head movements to induce movement-induced time-varying magnetic fields and were then tested for neurocognitive function in six domains.
The researchers found that attention and concentration (reflected by increased reaction times) and visuospatial orientation (reflected by nausea or dizziness) were negatively affected. Attention and concentration were most affected when high working memory performance was required, ranging from 5.0 to 21.1 percent per Tesla exposure. Visuospatial orientation was affected by 46.7 percent per Tesla exposure (P = 0.05).
"These findings support the hypothesis that head movement in a spatially heterogeneous static magnetic stray field up to one Tesla does temporarily affect neurocognitive functioning," van Nierop and colleagues write. "However, the exact implications and mechanisms of these subtle acute neurocognitive effects in practical settings remain unclear."
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