Olfactory-driven beta band entrainment of limbic circuitry during neonatal development

Cognitive processing relies on the functional refinement of the limbic circuitry during the first two weeks of life. During this developmental period, when most sensory systems are still immature, the sense of olfaction acts as "door to the world", providing the main source of environmental inputs. However, it is unknown whether early olfactory processing shapes the activity in the limbic circuitry during neonatal development. Here, we address this question by combining simultaneous in vivo recordings from the olfactory bulb (OB), lateral entorhinal cortex (LEC), hippocampus (HP), and prefrontal cortex (PFC) with olfactory stimulation as well as opto- and chemogenetic manipulations of mitral/tufted cells (M/TCs) in the OB of non-anesthetized neonatal mice. We show that the neonatal OB synchronizes the limbic circuity in the beta frequency range. Moreover, it drives neuronal and network activity in LEC, as well as subsequently, HP and PFC via long-range projections from mitral cells (MCs) to HP-projecting LEC neurons. Thus, OB activity shapes the communications within limbic circuits during neonatal development.