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Updated: Sep 13, 2025
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Generation and On-Demand Initiation of Acute Ictal Activity in Rodent and Human Tissue
Published on: January 19, 2019
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Interneuron-Driven Ictogenesis in the 4-Aminopyridine Model: Depolarization Block and Potassium Accumulation Initiate
Elena Yu Proskurina1, Julia L Ergina1, Aleksey V Zaitsev1
1Laboratory of Molecular Mechanisms of Neural Interactions, Sechenov Institute of Evolutionary Physiology and Biochemistry of RAS, 194223 Saint Petersburg, Russia.
International Journal of Molecular Sciences
|July 29, 2025
Summary
Fast-spiking interneurons initiate seizures by entering depolarization block, triggering pyramidal cell firing and subsequent ictal discharges. This dysfunction in inhibitory neurons is key to seizure generation.
Area of Science:
- Neuroscience
- Epilepsy Research
- Cellular Electrophysiology
Background:
- The precise mechanisms driving seizure initiation are not fully understood.
- The role of inhibitory interneurons in seizure generation presents a paradox.
- Fast-spiking interneurons are crucial for brain function but implicated in epilepsy.
Purpose of the Study:
- To elucidate the role of fast-spiking interneurons in ictal discharge initiation.
- To identify the sequence of events leading to seizure onset.
- To investigate region-specific differences in seizure generation mechanisms.
Main Methods:
- Simultaneous whole-cell recordings of interneurons and pyramidal neurons.
- Extracellular potassium ([K+]o) monitoring in mouse entorhinal cortex-hippocampal slices.
- Utilized the 4-aminopyridine model for inducing epileptiform activity.
Main Results:
- Interneurons exhibited high-frequency firing before entering depolarization block (DB).
- DB onset correlated with the peak rate of extracellular potassium accumulation.
- Pyramidal cells fired synchronously after interneuron DB, initiating ictal discharges.
- Entorhinal cortex neurons fired synchronously during ictal events, unlike hippocampal CA1 neurons.
Conclusions:
- Interneuron depolarization block acts as a temporal switch for ictogenesis.
- Disinhibition and potassium-mediated depolarization trigger synchronous pyramidal neuron activity.
- Fast-spiking interneuron dysfunction is a potential therapeutic target for focal epilepsy.
Keywords:
4-AP modeldepolarization blockdisinhibitionentorhinal cortexepilepsyfast-spiking interneuronshippocampal CA1in vitro electrophysiologypotassium dynamicsseizure initiationMore Related Videos
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