"Those considerations gave rise to the excitation/inhibition (E/I) imbalance theory, whereby increased excitation, decreased inhibition, or both favor a hyperexcitable state and an increased propensity for seizure generation and epileptogenesis."
Directly defines the E/I imbalance paradigm in which increased excitation and/or decreased inhibition favor hyperexcitability, the conserved amplifier step. Evidence source is OTHER because this is a review article.
"In the brain, GABA is a major inhibitory neurotransmitter and plays a pivotal role in maintaining E/I balance."
Establishes GABAergic signaling as the principal inhibitory arm whose loss contributes to E/I imbalance in epilepsy. Evidence source is OTHER because this is a review article.