Modeling the calcium spike as a threshold triggered fixed waveform for synchronous inputs in the fluctuation regime.
Modeling the layer 5 pyramidal neuron as a system of three connected isopotential compartments, the soma, proximal, and distal compartment, with calcium spike dynamics in the distal compartment following first order kinetics, we are able to reproduce in-vitro experimental results which demonstrate the involvement of calcium spikes in action potentials generation. To explore how calcium spikes affect the neuronal output in-vivo, we emulate in-vivo like conditions by embedding the neuron model in a regime of low background fluctuations with occasional large synchronous inputs. In such a regime, a full calcium spike is only triggered by the synchronous events in a threshold like manner and has a stereotypical waveform. Hence, in such a regime, we are able to replace the calcium dynamics with a simpler threshold triggered current of fixed waveform, which is amenable to analytical treatment. We obtain analytically the mean somatic membrane potential excursion due to a calcium spike being triggered while in the fluctuating regime. Our analytical form that accounts for the covariance between conductances and the membrane potential shows a better agreement with simulation results than a naive first order approximation.
Institute for Advanced Simulation (IAS-6) and Institute of Neuroscience and Medicine (INM-6) and JARA BRAIN Institute I, Jülich Research Centre Jülich, Germany ; Faculty of Biology, Albert-Ludwig University of Freiburg Freiburg im Breisgau, Germany ; Bernstein Center Freiburg, Albert-Ludwig University of Freiburg Freiburg im Breisgau, Germany.
Yansong
Y
Chua
Institute for Advanced Simulation (IAS-6) and Institute of Neuroscience and Medicine (INM-6) and JARA BRAIN Institute I, Jülich Research Centre Jülich, Germany ; Bernstein Center Freiburg, Albert-Ludwig University of Freiburg Freiburg im Breisgau, Germany ; Faculty of Psychology, Institute of Cognitive Neuroscience, Ruhr-University Bochum Bochum, Germany.
Abigail
A
Morrison
Institute for Advanced Simulation (IAS-6) and Institute of Neuroscience and Medicine (INM-6) and JARA BRAIN Institute I, Jülich Research Centre Jülich, Germany.
Moritz
M
Helias
calcium spike approximation; calcium spike as threshold triggered fixed waveform; calcium spike induced somatic voltage excursion; calcium spikes; pyramidal neuron