A model for neural activity in the absence of external stimuli

Speaker: Aline Duarte - IME-USP
Date: Mar 12, 2015
Time: 14h00
Local: Numec´s multipurpose room

Abstract: We study a stochastic process describing the continuous time evolution of the membrane potentials of finite system of neurons in the absence of external stimuli. The values of the membrane potentials evolve under the effect of chemical synapses, electrical synapses and a leak current. The evolution of the process can be informally described as follows. Each neuron spikes randomly following a point process with rate depending on its membrane potential. When a neuron spikes, its membrane potential is immediately reset to a resting value. Simultaneously, the membrane potential of the neurons which are influenced by it receive an additional positive value. Furthermore, between consecutive spikes, the system follows a deterministic motion due both to electrical synapses and the leak current. Electrical synapses push the system towards its average potential, while the leak current attracts the membrane potential of each neuron to the resting value. We show that in the absence leakage the process converges exponentially fast to
an unique invariant measure, whenever the initial configuration is non null. More interesting, when leakage is present, we proved the system stops spiking after a finite amount of time almost surely. This implies that the unique invariant measure is supported only by the null configuration.

Key words: piecewise deterministic Markov process, limiting distribution, neuronal systems



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