Dynamics of high-frequency synchronization during seizures
Giri P Krishnan1, Gregory Filatov, Maxim Bazhenov
1Department of Cell Biology and Neuroscience, University of California, Riverside, California 92521, USA.
Journal of Neurophysiology
|February 22, 2013
Summary
Epileptic seizures involve neuronal synchrony. This study found high-frequency brain activity synchrony decreases during seizures, while low-frequency synchrony increases, depending on electrode proximity to the seizure focus.
Area of Science:
- Neuroscience
- Computational Neuroscience
- Epilepsy Research
Background:
- Pathological neuronal firing synchronization is a hallmark of epileptic seizures.
- The impact of synchronization on high-frequency neuronal activity during seizures is not well understood.
Purpose of the Study:
- To investigate spatio-temporal synchronization patterns of both local field potentials (LFPs) and high-frequency multiunit activity during epileptiform discharges.
- To differentiate synchronization changes across various frequency bands and distances from seizure foci.
Main Methods:
- Utilized wide-band spectral analysis (up to 2,000 Hz) on multielectrode array recordings (up to 60 locations) from mouse hippocampus in vitro.
- Analyzed cross-coherence of neuronal activity during potassium-induced epileptiform discharges.
- Developed a computational model to validate experimental findings.
Main Results:
- Observed distinct LFP profiles with characteristic current sink/source distributions during epileptiform discharges.
- Found reduced cross-coherence for high-frequency activity (500-2,000 Hz) during epileptic bursts compared to baseline.
- Demonstrated distance-dependent cross-coherence: increased synchrony near foci, decreased synchrony further away for high frequencies.
- Observed the opposite trend for lower frequencies.
Conclusions:
- High-frequency neuronal activity synchrony decreases during epileptic bursts, contrasting with lower frequencies.
- Synchronization patterns are spatially dependent, varying with distance from the epileptic focus.
- Different intrinsic and synaptic mechanisms likely mediate paroxysmal synchronization across distinct frequency bands.
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