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Disorders of visual perception are frequent and disabling functional consequences of acquired brain injury (20-40%). They also have adverse effects on the assessment, diagnosis and treatment of other functional disorders. Most frequent are visual field disorders followed by disorders of visual acuity and contrast sensitivity, visual adaptation, color and visual space perception as well as of visual recognition. Multiple visual and/or additional cognitive disorders are most common. The differential diagnosis of cerebral visual disorders and an individually tailored and specific approach in the rehabilitation are therefore of great importance. Compensatory treatment methods are to be preferred because of their efficacy, ecological validity as well as a good cost-benefit ratio. [ABSTRACT FROM AUTHOR]

Following bilateral extrastriate damage to areas that include the suspected human homologue of V5/MT, the patient LM has a specific deficit in processing moving stimuli. She has difficulty detecting the movement or coding the velocity of single moving dots. Nevertheless, we find that she can report human actions in Johansson ''biological motion" displays. This requires the accurate coding of the direction and velocity of many moving dots. The implication is that structure can be extracted from motion in regions of visual cortex other than those traditionally associated with motion processing. However, she cannot report the spatial disposition of the actors whose actions she has recognized, not their movement in depth relative to her. A possible interpretation is that coding in these additional regions is primarily object-centred. Adding a small number of random stationary ''noise" dots to the display prevents her from identifying the actions, suggesting that segregation by motion is implemented within the traditional movement areas. [ABSTRACT FROM AUTHOR]

In a patient with damage to the right occipital lobe and to the splenium of the corpus callosum, an incomplete colour anopia in the left upper quadrants and a colour anomia was found for the complete left visual hemifield beyond 2 degrees eccentricity. The patient had no difficulty in recognising coloured targets when presented in the periphery of the left visual hemifield and in the foveal region, but could not name them correctly. The results suggest that the lesion of the splenium of the corpus callosum disconnects the right visual cortex from the language areas of the left hemisphere, and the specific disturbance of colour naming is the consequence. [ABSTRACT FROM AUTHOR]

Patients with postchiasmatic visual field defects were trained at the border of their visual field. Using a psychophysical method, light-difference thresholds were determined repeatedly in this visual field area. Improvement in contrast sensitivity and increase in size of the visual field could be obtained by this training procedure. The improvement was confined to the trained visual field area and showed interocular transfer indicating its central nature. Althoughh only contrast sensitivity was trained, the observed improvement was not limited to this visual function. Visual acutity, critical flicker fusion, and colour perception also showed and improvement suggesting an association of these functions. The improvement was restricted to the training period-no spontaneous recovery was observed between or after the periods of training. It is suggested that a lesion in the central visual system does not always result in a complete and permanent loss of function. The critical level of function that normally has to be reached for sufficient neuronal sensitivity may be obtained by systematic visual stimulation in the area between the intact and blind parts of the visual field. This increase in neuronal sensitivity leads to an improvement in visual performance. [ABSTRACT FROM AUTHOR]

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Copyright of Journal of Neurology is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)