Stephanie Rotzer
“2 x 3 = 4”: Neural Correlates in Children with Developmental Dyscalculia
Authors
Stephanie Rotzer (University Children's Hospital Zurich)
Developmental dyscalculia (DD) is a specific learning disability affecting the acquisition of mathematical skills in children with otherwise normal intelligence. Despite the high prevalence of 5-6 % in normal school population, little is known about the neural underpinnings of DD.
Functional brain imaging (fMRI) studies with typically achieving adults have identified parietal, frontal and anterior cingulate components to be involved in the performance of arithmetic tasks.
Our fMRI results indicated that children with DD show reduced brain activation in almost the entire fronto-parietal network during approximate calculation. Voxel-based morphometry with an optimization of the spatial segmentation and normalization (OVBM) was applied to 12 children with DD (9.3?0.2 years) and 12 control children without any learning disabilities (9.7?0.2 years) to identify volume differences in cerebral gray and white matter. Brain analysis indicated reduced gray matter volume in right parietal and bilateral frontal areas. The volume differences in frontal regions, especially the anterior cingulum, refer to early impairments of the attentional system and working memory, which might have a negative effect on the acquisition of number representation and number processing capacities. These findings support the hypothesis that working memory plays a central role in mathematical achievement and that its impairment may lead to a failure to construct a reliable semantic network of arithmetic facts.
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Sven Bölte
An fMRI- Study of Locally Oriented Perception in Autism:
Authors
Sven Bölte (University of Frankfurt
)
Daniela Hubl (University Hospital Berne
)
Thomas Dierks (University Hospital Berne
)
Martin Holtmann (University of Frankfurt
)
Fritz Poustka (University of Frankfurt)
Autism spectrum conditions have been associated with enhanced local processing on visual tasks. Originally, the notion is based on the observation of peak performance of individuals with autism on the Block Design Test (BDT) from the Wechsler Intelligence Scales. The neurofunctional correlates of local oriented bias on this test in autism have not yet been established, although there is evidence that alterations in early visual cortex could account for this cognitive mechanism. Functional MRI was used to analyze hemodynamic responses in the striate and extrastriate visual cortex during BDT performance and a color counting control task in seven subjects with autism and seven healthy controls. Processing of the BDT in autism was accompanied by lower blood oxygenation level-dependent signal change in the right ventral quadrant of V2. Findings indicate that locally oriented processing of the BDT in autism is associated with altered response of angle and grating selective neurons, that serve shape representation, figure-ground and gestalt organization. Among other possible explanations, local bias and lower V2v activation may be consequence of attenuated top-down (voluntary) attentional feedback, leading to a rather stimulus driven percept and sensory gain of certain features of the stimulus.
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Mareike Altgassen
Intact event-based and impaired time-based Prospective remembering in Autistic Spectrum Disorders?
Authors
Mareike Altgassen (University of Zurich)
Prospective memory refers to the ability to execute previously formed intentions. Individuals with autistic spectrum disorders (ASD) often find it hard to organize and coordinate everyday activities due to impairments in time management, preparation of materials needed for execution of an activity and sequencing of actions. Thus, they have difficulties with planning ahead and possibly with prospective remembering.
This study investigated prospective memory performance in people with autistic spectrum disorder in an event-based (Experiment 1) and a time-based prospective memory task (Experiment 2). Participants completed various ability tests. The prospective memory test was embedded in a visuospatial working memory test and required participants to respond to an event (Experiment 1) or to certain target times (Experiment 2). No group effects were found regarding the event-based prospective memory task (Experiment 1), however, controls outperformed individuals with ASD on the time-based prospective memory task (Experiment 2). Consequently, individuals with ASD appear to be unimpaired in highly structured tasks (event-based task), but to have difficulties with more complex tasks that require self-initiated processes (time-based task).
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Mengia Dosch
Neural development of perspective taking in preadolescent children
Authors
Mengia Dosch (Childrens University Hospital)
Zurich
Peter Klaver (Childrens University Hospital Zurich)
Kerstin Bucher (Childrens University Hospital Zurich)
Ernst Martin (Childrens University Hospital)
Zurich
Thomas Loenneker (Childrens University Hospital Zurich)
The ability to understand and predict other people’s behavior through perspective taking is essential for social interaction. Previous neuroimaging studies in adults have investigated the neural correlates for self-referential and perspective taking processing and could show that adults recruit common and distinct functional and anatomical networks during judgments about the own and other individual’s mental or emotional states.
We explored the neural development in 12 healthy adults (age range 26-36 yrs.) and 39 children (8-13 yrs) during self referential and perspective taking processing. Our data showed that children need significantly more time for judgments about another person’s point of view than for judgments about their own. In particular, the reaction time decreases with age for processing for judgments about of someone else point of view as compared with judgments about the own point of view. According to these data we conclude that the efficiency of perspective taking is still under development during preadolescence age. I will further present functional brain imaging results that track these development changes.
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