Regional activation of human cerebral cortex upon an adaptation in mirror drawing.

To elucidate cerebral regions involved in adaptation to mirror drawing, changes in regional cerebral blood flow were measured using positron emission tomography at different levels of adaptation. A significant signal in subtraction images was localized in left Brodmann's area 45 (ventral sub-region of Broca's area) in the initial phase of the mirror drawing. This activity decreased as adaptation proceeded, and a small cluster in area 19 of the medial extrastriate cortex became significantly active. An after-effect of ca. 30 min of mirror-drawing was also detected in the right area 21 of the temporal association cortex. The results first demonstrated visuo-cortical regions where neurons might change their activity to evoke plastic response to the inverted vision.