Emotionally Charged Visually Evoked Magnetic Fields

Abstract

Electroencephalography  is  a  neuroimaging  technique  sensitive to emotional states, a feature widely utilized in neuropsychology. Magnetoencephalography, as a technique complementary to electroencephalography, also  has  the  potential  to  be  applied to cognitive and neuroscience. Nevertheless, magnetoencephalography systems based on superconducting quantum interference devices are expensive to operate, limiting their use to mainly exploratory research. Optically pumped magnetometers are small single-unit sensors offering some advantages over superconducting quantum interference devices. Their properties are important in the measurements of subtle brain responses and indicate the possibility of magnetoencephalography becoming widely used in the near future. We used both existing types of magnetoencephalography systems, those with superconducting quantum interference devices and those with optically pumped magnetometers, to study magnetic brain responses to emotional stimuli. We examined the early components of visually evoked fields in five healthy subjects exposed to emotionally charged pictures. Both magnetoencephalography systems revealed a consistent negativity bias, known from electroencephalography, with stronger responses to negative stimuli compared to positive ones. These findings suggest that magnetoencephalography, especially with optically pumped magnetometers due to their ease of use, may play a significant role in neuropsychology.