Neural and glial mechanisms of network instability in epilepsy.
| Mechanism/Domain | Principal cell type(s) | Key biological disturbance | Effect on network stability | Contribution to seizure emergence/epileptogenesis | Representative evidence type |
|---|---|---|---|---|---|
| Excitation–inhibition imbalance | Excitatory neurons, inhibitory interneurons | Excessive glutamatergic drive, weakened inhibitory restraint, altered synaptic balance, lowered firing thresholds | Favors recurrent excitation, hypersynchrony, and easier recruitment of neuronal populations into pathological discharge | Creates a foundational permissive state for seizure initiation and promotes network conditions that support recurrent epileptic activity [80, 163] | Molecular, electrophysiological, circuit, animal, and translational studies |
| GABAergic dysfunction | GABAergic interneurons, principal neurons | Reduced inhibitory tone, receptor subtype alterations, disturbed tonic/phasic inhibition, chloride dysregulation, paradoxical GABA effects | Weakens inhibitory containment, disrupts timing control, and reduces the capacity of circuits to restrain synchronized firing | Lowers seizure threshold and contributes to persistent instability by impairing one of the main mechanisms that normally confine excitation [55] | Receptor studies, electrophysiology, animal models, human tissue, and translational studies |
| Ion channel/intrinsic excitability changes | Neurons | Altered sodium, potassium, and calcium channel function; increased burst propensity; impaired repolarization; membrane instability | Increases firing probability, repetitive discharge, and synchrony across vulnerable circuits | Supports seizure generation by making neurons more responsive to input and more likely to enter stable hyperexcitable states [80, 129] | Genetic, molecular, electrophysiological, animal, and clinical studies |
| Astrocytic dysfunction | Astrocytes | Impaired potassium buffering, including Kir4.1/gap junction-related regulation; reduced GLT-1/EAAT2-mediated glutamate uptake; disturbed aquaporin-4-associated water and volume regulation; abnormal calcium signaling; altered ATP–adenosine signaling and gliotransmission | Destabilizes extracellular ionic and neurotransmitter homeostasis and promotes an environment permissive for hyperexcitability and synchronization | Amplifies seizure susceptibility and reduces network resilience by weakening the homeostatic constraints that normally limit propagation and support recovery [27, 82] | Cellular, imaging, animal, human tissue, and translational studies |
| Microglial activation | Microglia | Context-dependent activation states; cytokine and danger signaling, including IL-1β/IL-1R1, TNF-α, HMGB1–TLR4, P2X7, and NLRP3-related pathways; complement-mediated synaptic pruning/remodeling; inflammatory amplification | Converts local disturbance into broader inflammatory and synaptic destabilization and may prolong seizure-prone network states | Contributes to epileptogenic progression by linking tissue stress, immune signaling, and maladaptive remodeling to chronic vulnerability [100] | Cellular, immunological, animal, human tissue, and translational studies |
| Oligodendroglial/Myelin-related changes | Oligodendrocytes, oligodendroglial lineage cells, axons | Altered myelin integrity, disturbed conduction timing, impaired axonal metabolic support, white matter dysregulation | Affects signal propagation, timing precision, and large-scale synchrony across distributed circuits | May influence seizure spread, persistence, and network-level coordination, especially in chronic or distributed epileptic states [11] | White matter studies, animal models, imaging, developmental, and translational studies |
| Calcium dysregulation | Neurons, astrocytes, microglia, mitochondria-associated cellular systems | Excessive calcium influx, disturbed intracellular store signaling, astrocytic calcium abnormalities, calcium-linked stress and inflammatory signaling | Couples excitability to intracellular stress, gliotransmission, metabolic strain, and long-term remodeling | Serves as a cross-cutting mechanism that links acute seizures to chronic epileptogenic change across cell types and timescales [18, 166] | Molecular, imaging, electrophysiological, organoid, animal, and translational studies |
| Neuroinflammatory amplification | Microglia, astrocytes, neurons, endothelial/BBB-associated cells, immune-related signaling systems | Cytokine signaling, danger-associated responses, BBB dysfunction, immune crosstalk, persistent inflammatory priming | Lowers seizure threshold, weakens recovery mechanisms, and reinforces chronic instability through feedback loops | It helps drive the transition from transient disturbance to enduring epileptogenic states and supports persistence of seizure-prone networks [144] | Molecular, immunological, animal, human tissue, and clinical/translational studies |
MMN: Conceptualization, Writing—original draft, Writing—review & editing. The author read and approved the submitted version.
The author declares that there are no conflicts of interest.
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