Neurogenesis in the Hippocampus of Patients with Temporal Lobe Epilepsy

The mobilization of endogenous neural stem cells in order to substitute lost neurons in the adult brain may reduce the negative effects of patients with chronic neurodegenerative diseases. However, abnormal neurogenesis may be harmful and could lead to the worsening of patients' symptoms. In the brains of patients and animal models with temporal lobe epilepsy (TLE), increased newly generated neurons in the subgranular zone (SGZ) at early stages after brain insults have been speculated to be involved in epileptogenesis. However, this argument is unsupported by evidence showing that (1) hippocampal neurogenesis is reduced at chronic stages of intractable TLE, (2) decreased neurogenesis is involved in epileptogenesis, and (3) spontaneous recurrent seizures occur before newly generated neurons are integrated into hippocampal neural pathways. Therefore, the hypothesis of increased neurogenesis in epileptogenesis may need to be re-evaluated. In this paper, we systemically reviewed brain neurogenesis and relevant molecules in the regulation of neurogenesis in SGZ. We aimed to update researchers and epileptologists on current progresses on pathophysiological changes of neurogenesis at different stages of TLE in patients and animal models of TLE. The interactions among neurogenesis, epileptogenesis and cognitive impairment, and molecules' mechanism involved in neurogenesis would also be discussed. Future research directions are proposed at the end of this paper.