DISSOCIATION OF OPHTHALMOKINETIC AND MELOKINETIC ATTENTION IN UNILATERAL NEGLECT

A line cancellation task was performed by 36 right brain-damaged patie nts with unilateral neglect under four different conditions: normal an d mirror-reversed view, with and without cueing. Two types of unilater al neglect were distinguished by directing ophthalmo- and melokinetic components of visuomanual scanning to opposite sides df the stimulus a rray. In ophthalmokinetic neglect, contralesional visual scanning of t he stimulus array was defective, while manual scanning was unimpaired. The converse was true of melokinetic neglect. Ophthalmokinetic neglec t was predominantly associated with posterior brain damage, while melo kinetic neglect was predominantly associated with frontal or subcortic al brain damage. In a few instances, cueing visuomanual scanning towar d the neglected side of the stimulus array converted ophthalmokinetic into melokinetic neglect, and vice versa. The results are held to be i ndicative of two components of space representation and to provide fur ther evidence of response-driven modulation of perceptual awareness.