Selective disturbance of movement vision after bilateral brain damage.
A patient who suffered bilateral posterior brain damage exhibited disturbance of movement vision in a rather pure form. The patient had no impression of movement in depth, and could only discriminate between a stationary and a moving target in the periphery of her otherwise intact visual fields. She had some movement vision in the central part of her visual fields, provided that target velocity did not exceed 10 deg/s. Neither did she possess visual movement after effects nor apparent (phi) visual movement. In addition, visually guided eye and finger movements were impaired. In contrast to the disturbance of movement perception in the visual modality, movement perception elicited by acoustic and tactile stimuli was not impaired. On the basis of the localization of the cerebral damage (as judged by CT scanning and neuropsychological testing) it is concluded that the observed disorder in movement vision is due to bilateral cerebral lesions affecting the lateral temporo-occipital cortex and the underlying white matter. The selectivity of the visual disturbance supports the idea that movement vision is a separate visual function depending on neuronal mechanisms beyond the primary visual cortex.