QUANTITATIVE RELATIONS BETWEEN PARIETAL ACTIVATION AND PERFORMANCE INMENTAL ROTATION

THE quantitative relationships between functional activation of the su perior parietal lobule (SPL) and performance in the Shepard-Metzler me ntal rotation task were investigated in 16 human subjects using magnet ic resonance (MR) imaging at high field (4 Tesla). Subjects were shown pairs of perspective drawings of three-dimensional objects and asked to judge whether they were the same or mirror images. Increased SPL ac tivation was associated with a higher proportion of errors in performa nce. The increase in errors, and the concomitant increase in SPL activ ation, could be due to an increased difficulty in, and therefore incre ased demands for, information processing at several stages involved in making a decision, including encoding of the visual images shown, men tally rotating them, and judging whether they are the same or mirror i mages.