High-gamma frequency-tagged magnetoencephalography reveals white matter-mediated dynamics of task-specific functional connectivity in spatial cognition

Fast periodic visual stimulation (FPVS) combined with magnetoencephalography (MEG) provides a powerful approach for extracting frequency-specific brain responses from perceptual processing areas. However, its application in cognitive paradigms—particularly those addressing visuospatial attention—remains underexplored. This study developed an FPVS-based line bisection paradigm to probe visuospatial cognition during passive viewing. Line stimuli were spatially modulated at high-gamma frequencies (70–90 Hz), centered at 80 Hz. Participants were instructed to fixate on the central segment (within the normal range of line bisection tasks). Source analysis in healthy volunteers revealed substantial activation in the right superior and inferior parietal lobules—particularly around the intraparietal sulcus—emerging 200–260 ms post-stimulus, providing clear evidence of stimulus-driven responses linked to visuospatial cognition. Connectivity analysis of neuronal dynamics revealed frequency-specific network interactions at 80 Hz, highlighting robust connections between parietal regions and occipital, frontal, and temporal cortices. These findings suggest dynamic engagement of long-range pathways, including the superior longitudinal and vertical occipital fasciculi, during visuospatial processing. Overall, FPVS-MEG enabled temporally precise and anatomically valid mapping of task-related networks. The observed connectivity patterns closely matched structural tracts, supporting that high-frequency MEG can non-invasively capture functionally meaningful large-scale brain networks with spatial resolution approaching that of tractography.