Visualization of human cognitive processing by MEG

Each non-invasive neuroimaging technique has its own inherent limitations resulting from temporal and special inaccuracies due to the nature of information that can be measured. While functional magnetic resonance imaging (fMRI) provides excellent spatial localization of the brain activity up to sub-millimeter resolution, its temporal resolution is limited by the hemodynamic time constant. Conversely, magnetoencephalography (MEG), which measure temporal changes in neural current directly, has temporal resolution of a few milliseconds; however, its spatial accuracy is limited by the non-uniqueness of the biomagnetic inverse problem in which the spatial distribution of neural currents is estimated from the MEG field distributions outside of the head. In this paper, recent developments in multimodal neuroimaging are introduced to allow for the reconstruction of human brain dynamics with high spatial accuracy without compromising temporal resolution. Specifically, we describe a technique to combine data from MEG, MRI and fMRI to visualize human higher order visual processing while perceiving a three-dimensional (3-D) shape from two-dimensional (2-D) motion.