**Date: **
Thursday, March 29, 2012

**Speaker: **
Radu Grosu

**Venue: **IST Austria

Human ventricular cells have currently more then ten increasingly detailed differential equations models (DEM), ranging from four variables and 27 parameters to more than 90 variables and hundreds of parameters. The detailed DEMs encapsulate the most up-to-date knowledge about the ionic processes involved at the intra and inter cellular level. While their differential equations are relatively simple (often of the law of mass action type) the sheer number of variables and parameters they contain, makes their analysis and even realistic 3D simulation intractable. It is therefore necessary, to map such DEMs to reduced order DEMs, whose analysis is still tractable. Our preliminary work shows that achieving such a map is possible: one uses simplifying assumptions to systematically eliminate variables whose behavior is not observable in the property of interest. For example, one can reduce the number of variables of the most up-to-date description of the sodium channel by assuming that its subunits are independent (Hodgkin-Huxley assumption) and by observing the overall open-close probability of the channel only.