Apply granger causality test to determine connections within peridodics ATP stimulated KTaR-1 cell colony

Cells are constantly detecting their local chemical environment. It is important for cells to be able to detect the change of the environment and employ correct strategies to make correct response. During the chemosensing process, cell colony would be able to generate highly regulated, consistent response, but for individual cell, the response would be intrinsically stochastic. The highly regulated, consistent response is vital to maintain the normal functionality of organism or larger biological system. Here we aim to understand how communication would play a role in the chemosesing process. In particular, we study KTaR cells, an immortalized neuronal cell line, with periodic ATP stimulations. We systematically vary the concentration and period of the stimuli. By analyzing the resulted Ca2+ oscillation, we use Granger Causality test to determine the connection between cells in the cell colony and to reconstruct the communicational network with the cells. Our results show that the external stimuli modulates self-organized multicellular network in profound ways.