Neuronale Korrelate zerebral bedingter visueller Wahrnehmungsstörungen

Two aspects of visual processing are investigated in this work. First, the impact of unilateral occipito-temporal cortical lesions on object categorization, and second, the influence of top-down manipulation on object categorization in healthy subjects. Major visual object recognition deficits (object agnosia) are rare, and occur mainly after bilateral damage to ventral visual cortices. Most patients suffering from unilateral ventral lesions are clinically non-agnostic. We studied the effect of unilateral occipito-temporal lesions on object categorization and its underlying neural correlates. The findings indicate that unilateral ventral lesions lead to disturbed processing in the lesioned hemisphere, which affects object categorization in both visual hemifields. In healthy object categorization bottom-up and top-down influences interact. We investigated the combination of different top-down influences and their effect on rapid object categorization. The results implicate that different top-down manipulations interact strongly, which should be taken into account when interpreting categorization results.