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Prolonged fasting impairs neural reactivity to visual stimulation.
N Kohn1,2, A Wassenberg3,4, T Toygar3,5
1JARA Brain, Translational Brain Medicine, Julich, Aachen, Germany. nils.kohn@gmx.net.
Brain Structure & Function
|October 2, 2014
Summary
Overnight fasting significantly impacts brain activity and functional connectivity in visual networks. Controlling blood glucose levels is crucial for accurate functional magnetic resonance imaging (fMRI) studies, especially those involving attention.
Area of Science:
- Neuroscience
- Cognitive Neuroscience
- Neuroimaging
Background:
- Hypoglycemia (low blood glucose) affects the Blood-Oxygen-Level-Dependent (BOLD) signal.
- Low normal glucose levels may also influence BOLD signals and cognitive processing, potentially confounding fMRI results.
- Understanding glucose's impact on brain function is vital for accurate neuroimaging interpretation.
Purpose of the Study:
- To investigate the effects of overnight fasting versus elevated glucose on brain activation and functional connectivity.
- To determine if blood glucose levels modulate visual cortex activity and its network interactions.
- To assess the implications of fasting on fMRI sensitivity for attentional tasks.
Main Methods:
- A placebo-controlled, crossover, double-blind study involving 40 healthy subjects.
- Comparison of brain activation and functional connectivity under fasting (low glucose) and elevated glucose conditions.
- Analysis of BOLD signal changes and network associations during basal visual stimulation.
Main Results:
- Overnight fasting diminished the BOLD signal in higher-order occipital processing areas compared to elevated glucose.
- Functional connectivity between the visual cortex and attention-related areas was strengthened with elevated glucose.
- Fasting led to stronger coupling between visual areas and the inferior temporal gyrus.
Conclusions:
- Prolonged overnight fasting significantly alters brain activation and functional connectivity in visual networks.
- Blood glucose levels modulate neural activity and network interactions relevant to attention.
- Fasting status must be controlled to maintain fMRI design sensitivity in attention-related tasks.
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