Simultaneous EEG, fMRI, and behavior in typical childhood absence seizures
Rachel Berman1, Michiro Negishi, Matthew Vestal
1Department of Neurology, Yale University School of Medicine, New Haven, Connecticut 06520-8018, USA.
Insights
Typical absence seizures in children involve widespread brain network changes affecting attention and processing. This EEG-fMRI study reveals key cortical and subcortical alterations during these events.
Area of Science:
- Neuroscience
- Epilepsy Research
- Cognitive Neuroscience
Background:
- Absence seizures cause temporary consciousness impairment, characterized by spike-wave discharges (SWDs) on EEG.
- Previous EEG-fMRI studies identified brain network changes during SWDs, but not specifically during childhood absence seizures with impaired consciousness.
Purpose of the Study:
- To investigate functional magnetic resonance imaging (fMRI) changes during typical childhood absence seizures (CAE) with confirmed impaired consciousness.
- To correlate brain network activity with behavioral performance during absence seizures.
Main Methods:
- Simultaneous EEG-fMRI and behavioral testing (continuous performance task and repetitive tapping task) were performed in 37 children with CAE.
- EEG-fMRI data were analyzed during SWD episodes to identify signal changes in cortical and subcortical regions.
- Behavioral performance was assessed for attentional vigilance and motor tasks during seizure epochs.
Main Results:
- fMRI signal increases were observed in the thalamus, frontal cortex, and sensory/motor cortices during SWDs.
- fMRI signal decreases were noted in the parietal cortex, cingulate gyrus, and basal ganglia.
- Significant behavioral impairments (81% omission errors on CPT) correlated with widespread fMRI changes during seizures.
Conclusions:
- Typical absence seizures involve a distributed cortical-subcortical network crucial for attention and information processing.
- Understanding this network's dysfunction may enhance comprehension of cognitive deficits in CAE.
- This research could inform the development of novel therapeutic strategies for childhood absence epilepsy.
Purpose:
Absence seizures cause transient impairment of consciousness. Typical absence seizures occur in children, and are accompanied by 3-4-Hz spike-wave discharges (SWDs) on electroencephalography (EEG). Prior EEG-functional magnetic resonance imaging (fMRI) studies of SWDs have shown a network of cortical and subcortical changes during these electrical events. However, fMRI during typical childhood absence seizures with confirmed impaired consciousness has not been previously investigated.
Methods:
We performed EEG-fMRI with simultaneous behavioral testing in 37 children with typical childhood absence epilepsy (CAE). Attentional vigilance was evaluated by a continuous performance task (CPT), and simpler motor performance was evaluated by a repetitive tapping task (RTT).
Results:
SWD episodes were obtained during fMRI scanning from 9 patients among the 37 studied. fMRI signal increases during SWDs were observed in the thalamus, frontal cortex, primary visual, auditory, somatosensory, and motor cortex, and fMRI decreases were seen in the lateral and medial parietal cortex, cingulate gyrus, and basal ganglia. Omission error rate (missed targets) with SWDs during fMRI was 81% on CPT and 39% on RTT. For those seizure epochs during which CPT performance was impaired, fMRI changes were seen in cortical and subcortical structures typically involved in SWDs, whereas minimal changes were observed for the few epochs during which performance was spared.
Discussion:
These findings suggest that typical absence seizures involve a network of cortical-subcortical areas necessary for normal attention and primary information processing. Identification of this network may improve understanding of cognitive impairments in CAE, and may help guide development of new therapies for this disorder.
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