Intense synaptic activity between mitral and granule cells leads to precise spike timing during gamma oscillations in the olfactory bulb

Abstract

The olfactory bulb is the first neuronal relay transmitting olfactory stimuli to higher level cortical neural circuits. During a sniff, at the end of the inspiration, the olfactory bulb local field potential (LFP) oscillates at the gamma frequency range (40–60 Hz) [1]. Those oscillations are generated by dendrodendritic synapses between mitral and granule cells [2]. Mitral cells, the principal neurons, activate the granule cells wich in turn inhibit them. With this interplay, mitral cell action potentials occur at a preferential phase of the LFP cycle [2]. The timing of mitral cells action potentials is known to be precise during local field oscillations [3]. This is not the case when mitral cells are individually activated with a slowly varying input current, similar to the one produced by an olfactory stimulation [4]. How do synaptic interactions between mitral and granule cells affect the mitral cell spike timing precision within an LFP cycle?