Magnetoencephalographic measurement during two types of mental rotations of three-dimensional objects

The mental rotation is one of the most widely used for the study of higher human cognitive processes. However, the detailed mechanisms in the brain related to the mental rotation are still unknown. In the present study, magnetoencephalographic (MEG) activities related to the mental rotation of three-dimensional objects were measured by a whole head type of 306-channel SQUID system. Differences in functional localization in the brain between twoand three-dimensional (2-D and 3-D) rotation tasks of 3-D objects were compared in order to investigate the cognitive processes for visualization of hidden parts of 3-D objects, because only 3-D rotation requires the visualization of the hidden parts of the 3-D objects. Activities in the parietal association area were increased during the 3-D rotation task, compared with the 2-D rotation task. This result indicates that the parietal association area acts as important role for the visualization of hidden parts of visual stimuli.