Functional MRI and magnetoencephalographic studies on cortical activities during visually guided saccades

In this study, brain activities of subjects performing visually guided saccade tasks were measured and analyzed by functional magnetic resonance imaging (fMRI) and magnetoencephalography (MEG). Eight healthy subjects with normal and corrected-to-normal visual acuity participated in the experiments. An integrative fMRI-MEG method, in which the time-varying dipole moments of activated regions were reconstructed from measured MEGs, was applied to data acquired from both fMRI and MEG experiments. Sets of activated regions were determined by statistically analyzed fMRI data and used as spatial constraints for the integrative fMRI-MEG method. Dynamic recurrent neural activities in multiple cortical areas such as the V1/V2, V2/V3, frontal eye field, ventral intraparietal area, and Brodmann's area 7 could be successfully detected, suggesting that these cortical areas play an important role for visually guided saccades. It may also reflect visual feedforward and feedback processes among different functional visual areas.