Newborn neurons with hilar basal dendrites hallmark epileptogenic networks.

Basal dendrites are transiently present on developing newly generated granule cells in adult rats. In epileptic rats, basal dendrites often fail to retract, resulting in the generation of persisting hilar basal dendrites that have been proposed to contribute to hyperexcitability. Here, we demonstrate that the formation of hilar basal dendrites also occurs in the absence of seizures following induction of an epileptogenic neuronal network by amygdala kindling. The number of newly generated neurons with hilar basal dendrites was significantly increased 6-8 weeks after the last kindled seizure. Thus, even in periods without seizure activity, persistence of hilar basal dendrites presents a hallmark of hyperexcitable epileptogenic networks in the rodent brain and may contribute to disease progression.