Calcium Dynamics and Generation of Propagating Waves in a Coupled Ensemble of Neurons with Random Connection Strengths

Recent experimental investigations of the brain show that excitatory α-amino-3-hydroxy-5-methyl-4-isoxazdepropionic acid (AMPA) secreting neurons, inhibitory γ-aminobutyric acid (GABA) secreting neurons, and intracellular calcium play important roles in neural network activities. Specifically, they influence the synchronization and desynchronization of neural ensembles, calcium dynamics in neurons, the generation of waves which propagate along the network. To simulate these types of activities a neural network model is developed which takes into account AMPA and GABA synapses, intracellular calcium, and calcium stores. It is found that the neural network model produces different types of activities, synchronization and desynchronization of neural cells, and propagating waves which are observed in the experiments. The type of activity depends on the type of synapses, connection strengths, values of injected current, and calcium release rate from intracellular calcium store. A mechanism of propagating wave generation based on the reduced connectivity between neurons is proposed.