116 research outputs found
Distinct Visual Working Memory Systems for View-Dependent and View-Invariant Representation
Background: How do people sustain a visual representation of the environment? Currently, many researchers argue that a single visual working memory system sustains non-spatial object information such as colors and shapes. However, previous studies tested visual working memory for two-dimensional objects only. In consequence, the nature of visual working memory for three-dimensional (3D) object representation remains unknown. Methodology/Principal Findings: Here, I show that when sustaining information about 3D objects, visual working memory clearly divides into two separate, specialized memory systems, rather than one system, as was previously thought. One memory system gradually accumulates sensory information, forming an increasingly precise view-dependent representation of the scene over the course of several seconds. A second memory system sustains view-invariant representations of 3D objects. The view-dependent memory system has a storage capacity of 3–4 representations and the view-invariant memory system has a storage capacity of 1–2 representations. These systems can operate independently from one another and do not compete for working memory storage resources. Conclusions/Significance: These results provide evidence that visual working memory sustains object information in two separate, specialized memory systems. One memory system sustains view-dependent representations of the scene, akin to the view-specific representations that guide place recognition during navigation in humans, rodents and insects. Th
Relationship between spatial ability, visuospatial working memory and self-assessed spatial orientation ability: a study in older adults
This paper describes some novel spatial tasks and questionnaires designed to assess spatial and orientation abilities. The new tasks and questionnaires were administered to a sample of 90 older adults (41 males, age range 57–90), along with some other tests of spatial ability (Minnesota Paper Form Board, Mental Rotations Test, and Embedded Figures Test) and tests of visuospatial working memory (Corsi’s Block Test and Visual Pattern Test). The internal reliability of the new tasks and questionnaires was analyzed, as well as their relationship with the spatial and working memory tests. The results showed that the new spatial tasks are reliable, correlate with working memory and spatial ability tests and, compared with the latters, show stronger correlations with the self-report questionnaires referring to orientation abilities. A model was also tested (with reference to Allen et al. in Intelligence 22:327–355, 1996) in which the new tasks were assumed to relate to spatial ability and predict orientation abilities as assessed by the self-report measures
Sexual Orientation-Related Differences in Virtual Spatial Navigation and Spatial Search Strategies
A quantitative and qualitative review of the effects of testosterone on the function and structure of the human social-emotional brain
Indices of low-grade chronic inflammation correlate with early cognitive deterioration in an elderly Greek population
Elevated serum levels of adhesion molecules (AM) reflect low-grade
chronic inflammation and have been associated with several conditions of
neuronal damage. The aim of the present study was the investigation of
possible correlation between early cognitive decline and inflammatory
processes in the elderly as indicated by plasma C-reactive protein (CRP)
and AM levels. Thirty-seven subjects with dementia were selected from a
community-dwelling, genetically isolated, geriatric population (above 60
years of age) based on the Mini Mental State Examination scale (MMSE)
and the Diagnostic and Statistical Manual (DSM-IV) criteria. In
parallel, a group of 33 age-matched healthy controls were selected from
the same population. The levels of CRP (mgA), sICAM-1 (ng/ml) and
sVCAM-1 (ng/ml) were measured in the serum samples of both groups. Serum
concentrations of all three molecules sICAM-1, sVCAM-1 and CRP were
significantly higher in the dementia group when compared to controls
(656.78 +/- 161.51 versus 467.05 +/- 231.26, p < 0.01; 631.64 +/- 149.76
versus 449.04 +/- 285.27,p < 0.01; 1.53 +/- 0.97 versus 0.7221 +/- 0.61,
p < 0.01, respectively). Furthermore, a positive correlation was
observed between the three molecules studied and the degree of severity
of cognitive impairment. The findings of this study enhance the
hypothesis of the presence of an underlying inflammatory process leading
to cognitive deterioration and predisposing dementia in the elderly. The
present work supports the evaluation of inflammatory molecules as early
indicators of cognitive decline in elderly individuals. (C) 2005
Elsevier Ireland Ltd. All rights reserved
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