A VENTRAL PONTINE PATHWAY PROMOTES RHYTHMIC ACTIVITY IN THE MEDULLA OF NEONATE MICE

WE have developed in new-born mice a ventral tilted-horizontal slice p reparation for pontine stimulation and recording of spontaneous respir atory-like rhythmic trains of glutamatergic excitatory postsynaptic po tentials (EPSPs) in medullary neurons. Electrical stimulations (10-50 Hz for 100-500 ms) of the caudal pontine reticular formation triggered a burst of EPSPs, recycling of the rhythmic activity and persistent i ncrease of the rhythmic behaviour. These results identify a ventral po ntine pathway that promotes rhythm generating mechanisms in the medull a and probably derives from a population of lateral reticular neurons identified in the embryonic hindbrain and eliminated after inactivatio n of the early developmental gene Krox-20.