Thursday 08 Mar 2018: Dynamics Seminar: Coupling can increase the period of phantom bursters dramatically: a slow-fast analysis.
Morten Pedersen - University of Padua
Newman Red LT 14:30-15:30
Pancreatic beta-cells exhibit bursting electrical activity, which underlies insulin secretion. Isolated beta-cells show fast bursting with a period of a few seconds, whereas the burst period is much longer (tens of seconds) in beta-cells located in the pancreatic islets where they are electrically coupled. Mathematically, bursting in single beta-cells can be minimally described as a square-wave burster with one slow and two fast variables, which can be analyzed by a standard slow-fast analysis. Coupling between square-wave bursters can increase the burst period modestly, and the underlying mechanisms have been analyzed extensively with slow-fast methods.
The phantom burster model (Bertram et al., Biophys J 2000) was suggested to explain the difference between burst periods observed in single and coupled beta-cells. This model introduces two slow variables, and can exhibit bursting with period ranging from seconds to minutes by changing a single variable. I will show that coupling alone can increase the burst period by an order of magnitude in phantom bursters. The analysis of coupled traditional bursters gives important insight, and can – when coupled with the phantom mechanism - explain the dramatic increase in burst period. Our results give a natural explanation for the large difference in burst period between isolated and coupled beta-cells.