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Number processing in posterior cortical atrophy--a neuropsycholgical case study
M Delazer1, E Karner, L Zamarian
1Clinical Department of Neurology, Innsbruck Medical University, Innsbruck, Austria. margarete.delazer@uibk.ac.at
Neuropsychologia
|June 7, 2005
Summary
Posterior cortical atrophy (PCA) causes dementia with early onset and visual processing deficits. This study reveals specific numerical deficits linked to parietal lobe degeneration in PCA patients.
Area of Science:
- Neuroscience
- Cognitive Psychology
- Gerontology
Background:
- Posterior cortical atrophy (PCA) is a rare dementia syndrome with early onset.
- It is characterized by higher visual function disorders, including Balint's syndrome, visual agnosia, alexia, and agraphia.
Observation:
- A single case study investigated numerical deficits in a patient with PCA.
- Neurodegeneration in the parietal lobe, particularly on the right side, was correlated with these deficits.
Findings:
- Impairments were observed in visuo-spatial tasks and internal number representation access (e.g., mental bisection, approximation).
- A dissociation in arithmetic was noted: multiplication and addition facts were preserved, while subtraction and division were severely impaired.
- The study confirmed a strong link between spatial and numerical processing, and impaired number semantics.
Implications:
- This research highlights the modular organization of the semantic system, specifically number semantics.
- It provides further evidence for the clinical manifestations of PCA and its impact on numerical cognition.