Original Research Investigation of Higher-Order Cognitive Functions During Exposure to a High Static Magnetic Field J € oran Lepsien, PhD, 1 * Karsten Mu ¨ller, PhD, 1 D. Yves von Cramon, MD, 1,2 and Harald E. M € oller, PhD 1 Purpose: To test for potential changes in higher-order cognitive processes related to the exposure to a high static magnetic field. Materials and Methods: Twenty-four healthy volunteers participated in two experimental sessions inside a 3 Tesla (T) magnetic resonance imaging (MRI) magnet. During one session the magnetic field was ramped down. The tasks consisted of six well-established paradigms probing a va- riety of cognitive functions. Reaction times (RT) and accu- racies (AC) were recorded for statistical analysis. Results: The overall performance was very similar in both sessions. Strong task-specific effects (all P < 0.006) were consistent with previously published results. Direct com- parisons of task-specific effects between the two sessions (magnetic field on or off) remained insignificance for all paradigms (RT: all P > 0.196; AC: all P > 0.17; no correc- tions for multiple comparisons). Conclusion: The results did not indicate any apparent safety concerns with respect to cognitive performance in a static magnetic field of a typical whole-body magnet. In addition, comparisons of cognitive effects from testing sit- uations with and without exposure to high static mag- netic fields can be considered valid. Key Words: cognitive functions; magnetic resonance imaging; safety; static magnetic field J. Magn. Reson. Imaging 2012;000:000–000. V C 2012 Wiley Periodicals, Inc. FOR MORE THAN 20 years, functional MRI (fMRI) has been used to study the neural correlates of human behavior. To allow integration of data acquired in an MRI scanner with more traditional measures of cogni- tive psychology, such as reaction time (RT) and accu- racy (AC) acquired in an RT-lab, it is essential to assume that the data acquisition itself does not interfere with the cognitive functions investigated. Koch et al (1) demonstrated that the typical effect of a general slowing of RT in fMRI experiments can be attributed to factors like the changed spatial frame of reference or the unfamiliar and noisy environment inside an MRI magnet. However, in addition to such unspecific distracting factors from an uncomfortable environment, additional effects on cognitive perform- ance might result from physical parameters, in partic- ular static and time-varying electromagnetic fields applied during the scanning procedure. This latter point is of additional importance because it is directly related to on-going discussions on the safety of MRI in general (2). Subsequently, we focus on the exposure to a high static magnetic field during an MRI examination. With increasing field strength, transient sensory effects, such as the perception of magnetophos- phenes, a metallic taste, or vertigo-like sensations, are more frequently reported (3–6). The underlying mechanisms of these phenomena are probably not related to a direct effect on the central-nervous sys- tem but rather result from the induced currents affecting the retina (5), induction of currents in the tongue (7), or weak mechanical forces due to diamag- netic susceptibility differences between the vestibular organs and the surrounding fluid and induced cur- rents acting on the vestibular hair cells (8). With respect to cognitive functions, some studies have been conducted, but the results are inconclusive. Most researchers did not find significant effects related to field exposure (9–13). However, a few studies reported alterations of eye-hand coordination, visual contrast sensitivity, as well as visual and auditory working memory (14–17). Studies conducted so far differ substantially in their experimental protocol, which explains at least some of the inconsistencies: (i) Only two studies tested the participants inside the bore of the magnet (1,10). In all other studies, participants were tested either next to the magnet (but inside the magnet room) (9,11,14,15) or outside the magnet room after expo- sure (1,10,12,13). (ii) Some studies instructed the participants to perform controlled movements to induce effects related to motion in a magnetic field (i.e., a time-varying field) (11,14,15,17). (iii) Most 1 Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany. 2 Max Planck Institute for Neurological Research, Cologne, Germany. *Address reprint requests to: J.L., Max Planck Institute for Human Cognitive and Brain Sciences, Stephanstraße 1a, 04103 Leipzig, Ger- many. E-mail: lepsien@cbs.mpg.de Received November 15, 2011; Accepted May 8, 2012. DOI 10.1002/jmri.23727 View this article online at wileyonlinelibrary.com. JOURNAL OF MAGNETIC RESONANCE IMAGING 000:000–000 (2012) CME V C 2012 Wiley Periodicals, Inc. 1