  Epilepsy is a neurological disorder with recurrent seizures of complexity and
randomness. Until now, the mechanism of epileptic randomness has not been fully
elucidated. Inspired by the recent finding that astrocyte GTPase-activating
protein (G-protein)-coupled receptors could be involved in stochastic epileptic
seizures, we proposed a neuron-astrocyte network model, incorporating the noise
of the astrocytic second messager, inositol triphosphate (IP3) which is
modulated by the G-protein)-coupled receptor activation. Based on this model,
we have statistically analysed the transitions of epileptic seizures by
performing tens of simulation trials. Our simulation results show that the
increase of the IP3 noise intensity induces the depolarization-block epileptic
seizures together with an increase in neuronal firing frequency. Meanwhile, a
bistable state of neuronal firing emerges under certain noise intensity, during
which the neuronal firing pattern switches between regular sparse spiking and
epileptic seizure states. This random presence of epileptic seizures is absent
when the noise intensity continues to increase, accompanying with an increase
in the epileptic depolarization block duration. The simulation results also
shed light on the fact that calcium signals in astrocytes play significant
roles in the pattern formations of the epileptic seizure. Our results provide a
potential pathway for understanding the epileptic randomness.
