Connectivity and dynamics in the olfactory bulb

Dendrodendritic interactions between excitatory mitral cells (MCs) and inhibitory granule cells (GCs) in the olfactory bulb create a dense interaction network, reorganizing sensory representations of odors and, consequently, perception. Large-scale computational models are needed for revealing how the collective behavior of this network emerges from its global architecture. We propose an approach where we summarize anatomical information through dendritic geometry and density distributions which we use to calculate the probability of synapse between MCs and GCs, while capturing activity patterns of each cell type in the neural dynamical systems theory of Izhikevich. In this way, we generate an efficient, realistic large-scale model of the bulbar network. Our model reproduces known connectivity and functional properties of the bulb, and in turn predicts testable relationships between these two aspects of the bulb. Importantly, this allows us to explore the influence of the cortex on bulbar activity, demonstrating possible mechanisms by which centrifugal feedback to MCs or GCs influences bulbar activity, as well as how neurogenesis improves decorrelation without invoking cell death. Additionally, the methodology we describe here provides a tractable tool for other researchers.