"In the mammalian olfactory bulb, the inhibitory axonless granule cells (GCs) feature reciprocal synapses that interconnect them with the principal neurons of the bulb, mitral, and tufted cells. These synapses are located within large excitable spines that can generate local action potentials (APs) upon synaptic input (“spine spike”). Moreover, GCs can fire global APs that propagate throughout the dendrite. Strikingly, local postsynaptic Ca2+ entry summates mostly linearly with Ca2+ entry due to coincident global APs generated by glomerular stimulation, although some underlying conductances should be inactivated. We investigated this phenomenon by constructing a compartmental GC model to simulate the pairing of local and global signals as a function of their temporal separation ?t. These simulations yield strongly sublinear summation of spine Ca2+ entry for the case of perfect coincidence ?t = 0 ms. ..."
Model Type: Dendrite; Channel/Receptor; Synapse
Region(s) or Organism(s): Olfactory bulb
Cell Type(s): Olfactory bulb main interneuron granule MC GABA cell; Olfactory bulb main interneuron granule TC GABA cell
Currents: Ca pump; I Calcium; I K; I Sodium
Transmitters: Glutamate
Model Concept(s): Active Dendrites; Calcium dynamics; Coincidence Detection
Simulation Environment: NEURON; Python
Implementer(s): Aghvami, S. Sara [ssa.aghvami at gmail.com]
References:
Aghvami SS, Müller M, Araabi BN, Egger V. (2019). Coincidence Detection within the Excitable Rat Olfactory Bulb Granule Cell Spines. The Journal of neuroscience : the official journal of the Society for Neuroscience. 39 [PubMed]