Schwindel-Sprechstunde-Hamburg

Spezial-Ambulanz für Schwindel,
Gleichgewichts- und Augenbewegungsstörungen

Neurologie

Quantitative Untersuchung von Blickbewegungen während Visual imagery bei Hemianopikern und Normalprobanden.
Gbadamosi J, Oechsner U, Zangemeister WH: Neurologie & Rehabil 1997; 3: 165-173 Abstract.

Maladaptation of the visual system is a common and well-known finding after posterior territorial stroke. We examined the neuropsychological behaviour of eye movements using infrared oculography in ten patients with homonymous hemianopia after posterior stroke while viewing five complex images before and after a special training. For this purpose, the viewed images were divided into geometric (a priori) regions of interest (ROI) and into semantic (a posteriori) ROI according to the subfeatures of the scene. Each ROI was labeled, so the scanpath of image viewing produced a string of labels that was compared with those of ten healthy controls. Region string editing, vector string editing and Markov analysis was used to compare these strings. The results showed marked success in rehabilitating homonymous hemianopia patients after the special training, despite a long delay time between the lesion and the beginning of training. This improvement is particularly reflected by a higher string similarity during image viewing with the semantic a posteriori ROI in trained patients compared with controls. With regard to our results we postulate on the one hand that a striatal visual buffer may exist for a transitory representation of subfeatures of images in a spatial format. On the other hand there is evidence for an extrastriatal long-term memory. After training an accelerated filling of the visual buffer and/or a facilitated mobilisation of this information from the visual buffer could lead to improved top-down-processing in patients with homonymous hemianopia as a result of neurovisual rehabilitation, regardless of the time between the lesion and the beginning of the training.

download full text