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The selective inability to draw horizontal lines: a peculiar constructional disorder
D Grossi1, N A Fragassi, E Giani
1Department of Neurological Sciences, Federico II University, Naples, Italy.
Journal of Neurology, Neurosurgery, and Psychiatry
|July 1, 1998
Summary
This study details a unique case of constructional apraxia in degenerative dementia, revealing a novel dissociation in line drawing abilities. Horizontal line construction was impaired while vertical and oblique lines were spared, suggesting distinct neural pathways for spatial representation.
Area of Science:
- Neuroscience
- Cognitive Psychology
- Neurology
Background:
- Degenerative dementia can lead to various cognitive impairments, including constructional apraxia, affecting the ability to draw or assemble objects.
- Constructional apraxia typically involves difficulties in visuospatial processing and motor planning.
Observation:
- A patient with degenerative dementia presented with severe constructional apraxia.
- A unique dissociation was observed: impaired horizontal line construction contrasted with spared vertical and oblique line construction.
Findings:
- This horizontal-vertical line dissociation was consistent across various experimental conditions.
- The dissociation extended to both perceptual and representational spatial domains.
- This suggests a functional separation in the brain's representation of horizontal versus vertical spatial relations within an egocentric coordinate system.
Implications:
- The findings challenge existing models of visuospatial processing in constructional apraxia.
- This case provides novel insights into the neural underpinnings of spatial representation and coordinate systems.
- Further research can explore the specific neural mechanisms underlying this observed functional dissociation.