A lesion of cortical area V2 selectively impairs the perception of the direction of first-order visual motion

Lesions of area MT/V5 in monkeys and its presumed homologue, the motion are a, in humans impair motion perception, including the discrimination of the direction of global motion in random dot kinematograms. Here we report the results of similar tests on patient TF, who has a discrete and very small, unilateral infarct in the medial superior pare of the right occipital corte x. Structural MRI, co-registered in software with a standardized human brai n atlas, reveals that the lesion involves area V2. The patient was impaired in his retinotopically corresponding left lower quadrant on several motion tasks including discrimination in random dot kinematograms of direction, s peed and motion-defined discontinuity. He was also impaired on tasks select ively involving first-order motion based on luminance contrast but not on s econd-order motion based on texture contrast. The results show that even th ough area MT/V5 is intact, motion perception is abnormal and, in particular , his perception of first-order motion is impaired. NeuroReport 11:1039-104 4 (C) 2000 Lippincott Williams & Wilkins.