Dynamic Changes in Cortical Effective Connectivity Underlie Transsaccadic Integration in Humans

Due to saccadic eye movements the retinal image is abruptly displaced 2-4 times a second, yet we experience a stable and continuous stream of vision. It is known that saccades modulate neural processing in various local brain areas, but the question of how saccades influence neural communication between different areas in the thalamo-cortical system has remained unanswered. By combining transcranial magnetic stimulation with electroencephalography, we found that saccades were accompanied by dynamic changes in causal communication between different brain areas in humans. These changes were anticipatory; they began before the actual eye movement. Compared with fixation, communication between posterior cortical areas was first briefly enhanced during saccades, but subsequently peri-saccadic information did not ignite sustained activity in fronto-parietal cortices. This suggests that the brain constructs a spatially stable and temporally continuous stream of conscious vision from discrete fixations by restricting the access of peri-saccadic visual information to sustained processing in fronto-parietal cortices.