Universität zu Köln

Neitzel, Julia ORCID: 0000-0001-5739-466X, Ortner, Marion, Haupt, Marleen ORCID: 0000-0003-1683-8679, Redel, Petra, Grimmer, Timo, Yakushev, Igor, Drzezga, Alexander, Bublak, Peter, Preul, Christoph, Sorg, Christian and Finke, Kathrin (2016). Neuro-cognitive mechanisms of simultanagnosia in patients with posterior cortical atrophy. Brain, 139. S. 3267 - 3281. OXFORD: OXFORD UNIV PRESS. ISSN 1460-2156

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Abstract

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

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Neitzel, Julia UNSPECIFIED orcid.org/0000-0001-5739-466X UNSPECIFIED Ortner, Marion UNSPECIFIED UNSPECIFIED UNSPECIFIED Haupt, Marleen UNSPECIFIED orcid.org/0000-0003-1683-8679 UNSPECIFIED Redel, Petra UNSPECIFIED UNSPECIFIED UNSPECIFIED Grimmer, Timo UNSPECIFIED UNSPECIFIED UNSPECIFIED Yakushev, Igor UNSPECIFIED UNSPECIFIED UNSPECIFIED Drzezga, Alexander UNSPECIFIED UNSPECIFIED UNSPECIFIED Bublak, Peter UNSPECIFIED UNSPECIFIED UNSPECIFIED Preul, Christoph UNSPECIFIED UNSPECIFIED UNSPECIFIED Sorg, Christian UNSPECIFIED UNSPECIFIED UNSPECIFIED Finke, Kathrin UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-253592
DOI:	10.1093/brain/aww235
Journal or Publication Title:	Brain
Volume:	139
Page Range:	S. 3267 - 3281
Date:	2016
Publisher:	OXFORD UNIV PRESS
Place of Publication:	OXFORD
ISSN:	1460-2156
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language PARAMETER-BASED ASSESSMENT; VISUAL WORKING-MEMORY; ALZHEIMERS-DISEASE; ATTENTIONAL FUNCTIONS; PROCESSING CAPACITY; OLDER-ADULTS; SPEED; TVA; IMPAIRMENT; COMPONENTS Multiple languages Clinical Neurology; Neurosciences Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/25359