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Atypical hemispheric dominance for attention: functional MRI topography
Agnes Flöel1, Andreas Jansen, Michael Deppe
1Human Cortical Physiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892-1430, USA. fleola@ninds.nih.gov
Summary
Atypical brain organization shows that the pattern of neural activation within a hemisphere, not just the side, is key for spatial attention and language processing. This finding advances our understanding of brain lateralization.
Area of Science:
- Neuroscience
- Cognitive Neuroscience
- Neuroimaging
Background:
- The right hemisphere typically dominates spatial attention, but atypical lateralization of spatial attention and language exists in healthy individuals.
- Understanding the neural basis of atypical hemispheric dominance for spatial attention and language is limited.
- Previous screening identified individuals with atypical visuospatial attention and language lateralization using functional Doppler ultrasonography.
Purpose of the Study:
- To investigate the regional distribution of neural activation in individuals with atypical hemispheric dominance for spatial attention and language.
- To compare brain activation patterns during a spatial attention task between atypical and typically organized individuals.
Main Methods:
- Functional magnetic resonance imaging (fMRI) was used to study brain activation patterns.
- Participants included right-handed individuals with atypical lateralization (language right, attention left; or both functions right-lateralized) and controls with typical organization.
- A spatial attention task was administered during fMRI scanning.
Main Results:
- Individuals with inverted lateralization (language right, attention left) recruited left-hemispheric areas for attention, mirroring control activation in the right hemisphere.
- Individuals with right-hemisphere dominance for both language and attention showed comparable attentional network activation to controls.
- Hemispheric side was less critical than the intrahemispheric pattern of activation.
Conclusions:
- The intrahemispheric pattern of neural activation, rather than the specific cerebral hemisphere, is crucial for the neural underpinnings of language and attention.
- These findings challenge traditional views of strict hemispheric dominance and highlight the flexibility of brain organization.
- This research provides new insights into the neural mechanisms supporting cognitive functions in diverse brain organizations.