MEG study of occipital lobe function changes according to task demand using a visual Go/No-Go paradigm

Brain function changes during stimulus processing according to the task demand were investigated by recording magnetoencephalographic (MEG) responses in the occipital lobe using a visual Go/No-Go paradigm in 14 healthy volunteers. Nine out of the 14 subjects demonstrated three MEG response peaks of 100, 160, and 230 ms latencies after stimulus onsets, and their root-mean-square (RMS) values decreased in the order of the selective-response, all-response, and no-response tasks. The estimated dipoles for the first peak were mostly located around the calcarine sulcus in all the three tasks, and those for the third peak were located more anteriorly in the all-response and selective-response tasks than in the no-response task. The results are interpreted to demonstrate the task-demand-related changes in brain function during visual stimulus processing in the occipital cortex.