Coordinated electrical activity in the olfactory bulb gates the oscillatory entrainment of entorhinal networks in neonatal mice

In contrast to other sensory systems, the olfactory system is already fully mature at birth, controlling mother-offspring interactions and neonatal survival. We investigate its role in neonatal network entrainment, focusing on the structural and functional connectivity between olfactory bulb (OB) and lateral entorhinal cortex (LEC) – which we previously identified as a driving force in the entrainment of neonatal limbic circuitry. We show that reciprocal connectivity between OB and LEC is present at neonatal age and a continuous slow respiration-related rhythm and discontinuous theta bursts characterize the activity in the neonatal OB. Moreover, mitral cell-dependent theta bursts in OB drive neonatal entorhinal activity and odors boost theta and beta coupling in neonatal OB-LEC circuits.