Role of astrocytes in synchronized neuronal bursting

Ravi Kumar^1*, Yu-Ting Huang³, Chun-Chung Chen³, Shun-Fen Tzeng², C.K Chan³

¹Interdisciplinary Neuroscience, Taiwan International Graduate Program, Academia Sinica and National Cheng Kung University, Taipei, Taiwan
²Department of Life Sciences, National Cheng Kung University, Tainan, Taiwan
³Institute of Physics, Academia Sinica, Taipei, Taiwan

* Presenter:Ravi Kumar, email:ravikumar@gate.sinica.edu.tw

Synchronized bursting (SB), a collective dynamics of neurons is related to brain functions. Its underlying mechanism still remains unclear. Recent studies provide sufficient evidence that astrocytes (glial cells) participate in synaptic transmissions. However, the role of astrocytes in SB is not yet well understood. Here, we investigated collective dynamics of neurons by using neuron-glia mix cell-culture developed on multi-electrode arrays (MEA) system. We found that properties of SB events such as bursting rate and burst duration depend on the activities of astrocytic glutamate transporters. By including the glutamate traffics related to astrocytes, we developed a tripartite TUMG model based on the Tsodyks, Uziel and Markram's bipartite synapse model to match with our experimental observations. Simulation results of the TUMG model with parameters matched with experimental firing and bursting patterns, suggest that the astrocytes maintain a homeostatic range of glutamate available for neurons that affect the firing dynamics of SB. They regulate synaptic transmissions by fixing the total amount of available glutamate in the pre-synaptic neuron which in turn controls the dynamics of SB.

Keywords: neuron-astrocyte interaction, glutamate transporters, multi-electrode arrays, tripartite synapse, glutamate trafficking