Neuro-cognitive mechanisms of simultanagnosia in patients with posterior cortical atrophy.

摘要: Posterior cortical atrophy is dominated by progressive degradation of parieto-occipital grey and white matter, represents in most cases a variant Alzheimer’s disease. Patients with posterior are characterized increasing higher visual visuo-spatial impairments. In particular, key symptom simultanagnosia i.e. the inability to perceive multiple objects at same time. Two neuro-cognitive mechanisms have been suggested underlie simultanagnosia, either reduced short-term memory capacity or decreased processing speed possibly resulting from matter impairments over above damage brain areas. To test these distinct hypotheses, we investigated group 12 patients suffering homogenous lesion sides cortices varying severity loss. More specifically, (i) tested whether impaired symptoms simultanagnosia; (ii) assessed link damage; (iii) integrated those findings into model atrophy. this end, simultaneous perception was mostly positive disease biomarkers healthy age-matched controls. Critical outcome measures were identification overlapping relative non-overlapping figures performance tests sensitive simultanagnosia. Using whole report briefly presented letter arrays based on mathematically formulated ‘Theory Visual Attention’, furthermore quantified parameters speed. Grey voxel-based morphometry analyses structural magnetic resonance data. All showed severe deficits perception. Compared controls, observed specific slowing speed, while preserved. regression analysis, identified as only significant predictor that explained high degree variance (70–82%) across tasks. also indicative for more reading scene comprehension. Voxel-based yielded extensive reductions thalamic Importantly, individual left superior parietal lobe, but not any region, associated Based findings, propose commonly leads which underlies overt clinical simultanagnosia. * Abbreviations : BORB Birmingham Object Recognition Battery PCA atrophy SPT simultaneous-perception task STM short term memory TVA Theory Attention VBM morphometry VOSP Space Perception Battery