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Abnormal brain activation in neurofibromatosis type 1: a link between visual processing and the default mode network.
Inês R Violante1, Maria J Ribeiro, Gil Cunha
1Visual Neuroscience Laboratory, Institute of Biomedical Research in Light and Image, Faculty of Medicine, University of Coimbra, Coimbra, Portugal.
Plos One
|June 23, 2012
Summary
Neurofibromatosis type 1 (NF1) patients show impaired early visual processing, particularly in the magnocellular pathway. This deficit, present in both children and adults, is linked to altered default mode network activity, potentially explaining cognitive issues in NF1.
Area of Science:
- Neuroscience
- Neuroimaging
- Genetics
Background:
- Neurofibromatosis type 1 (NF1) is a common genetic disorder.
- Cognitive deficits, especially visuospatial, are frequent in NF1.
- Underlying neurophysiological alterations in early visual processing remain unclear.
Purpose of the Study:
- To investigate early cortical visual pathway function in NF1 using fMRI.
- To differentiate the roles of magnocellular (M) and parvocellular (P) pathways in NF1 visual processing.
- To explore the relationship between visual processing deficits and the default mode network (DMN) in NF1.
Main Methods:
- Functional magnetic resonance imaging (fMRI) was used in children and adults with NF1 and matched controls.
- Two stimulus types were employed to selectively activate M and P visual pathways.
- Hemodynamic responses were analyzed in early visual areas (V1, V2, V3) and across the cortical volume.
Main Results:
- NF1 patients exhibited deficient activation in the low-level visual cortex for both stimulus types.
- These visual processing deficits were consistent across age groups (children and adults).
- During M-biased stimulation, NF1 patients showed impaired deactivation of DMN midline regions.
Conclusions:
- Early visual processing, particularly magnocellular pathway function, is impaired in NF1.
- This magnocellular pathway deficit is associated with abnormal default mode network activity.
- These findings offer a neural basis for visuospatial and attentional deficits in NF1 and potentially other neuropsychiatric disorders.
