Bursting mitral cells time the oscillatory coupling between olfactory bulb and entorhinal networks in neonatal mice

The Journal of Physiology, vol. 598, pp. 5753–5769

Abstract

KEY POINTS: During early postnatal development, mitral cells show either irregular bursting or non-bursting firing patterns Bursting mitral cells preferentially fire during theta bursts in the neonatal olfactory bulb, being locked to the theta phase Bursting mitral cells preferentially fire during theta bursts in the neonatal lateral entorhinal cortex and are temporally related to both respiration rhythm- and theta phase Bursting mitral cells act as a cellular substrate of the olfactory drive that promotes the oscillatory entrainment of entorhinal networks ABSTRACT: Shortly after birth, the olfactory system provides not only the main source of environmental inputs to blind, deaf, non-whisking and motorically-limited rodents, but also the drive boosting the functional entrainment of limbic circuits. However, the cellular substrate of this early communication remains largely unknown. Here, we combine in vivo and in vitro patch-clamp and extracellular recordings to reveal the contribution of mitral cell (MC) firing to early patterns of network activity in both the neonatal olfactory bulb (OB) and the lateral entorhinal cortex (LEC), the gatekeeper of limbic circuits. We show that MCs predominantly fire either in an irregular bursting or non-bursting pattern during discontinuous theta events in the OB. However, the temporal spike-theta phase coupling is stronger for bursting than non-bursting MCs. In line with the direct OB-to-LEC projections, both bursting and non-bursting discharge augments during co-ordinated patterns of entorhinal activity, albeit with higher magnitude for bursting MCs. For these neurons, temporal coupling to the discontinuous theta events in the LEC is stronger. Thus, bursting MCs might drive the entrainment of the OB-LEC network during neonatal development.

Authors 4

1. Johanna K. Kostka corresponding

   University Medical Center Hamburg-Eppendorf

   Affiliation as printed

   Institute of Developmental Neurophysiology Center for Molecular Neurobiology University Medical Center Hamburg‐Eppendorf Hamburg Germany

   Institute of Developmental Neurophysiology, Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany

2. Sabine Gretenkord

   University Medical Center Hamburg-Eppendorf

   Affiliation as printed

   Institute of Developmental Neurophysiology Center for Molecular Neurobiology University Medical Center Hamburg‐Eppendorf Hamburg Germany

   Institute of Developmental Neurophysiology, Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany

3. Marc Spehr Aachen Department of Chemosensation Institute of Biology II Department of Chemosensation Institute of Biology II

   RWTH Aachen University

   Affiliation as printed

   Department of Chemosensation Institute of Biology II, Rheinisch‐Westfalische Technische Hochschule Aachen Aachen Germany

   Department of Chemosensation, Institute of Biology II, Rheinisch-Westfalische Technische Hochschule Aachen, Aachen, Germany

4. Ileana L. Hanganu‐Opatz corresponding

   University Medical Center Hamburg-Eppendorf

   Affiliation as printed

   Institute of Developmental Neurophysiology Center for Molecular Neurobiology University Medical Center Hamburg‐Eppendorf Hamburg Germany

   Institute of Developmental Neurophysiology, Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany