Spontaneous activity in the perinatal trigeminal nucleus of the rat

The role of electrical activity in establishing appropriate connections in the trigeminal pathway remains controversial. We report here a novel observation of spontaneous activity in the perinatal trigeminal sensory nucleus between embryonic day (E) 16 to postnatal day (P) 8. Most of these spontaneous bursts had the same polarity and were of comparable amplitude to the trigeminal nerve-evoked response. This synchronized activity was abolished by bicuculline or kynurenic acid. Recording from the teased trigeminal root during the spontaneous bursts also showed a corresponding afferent depolarization. We speculate that the GABAergic depolarization of pre- and postsynaptic cells may contribute to the generation of the spontaneous activity and its propagation throughout the trigeminal sensory pathway, even in the absence of activity initiated from peripheral sensory receptors.