IMSc Webinar

Emergent patterns of activity in disordered biological systems: Role of heterogeneities in organizing the collective dynamics of excitable cell-assemblies and tissues

Ria Ghosh

IMSc, Chennai

Many physiologically critical functions are mediated by cells and tissue that are electrically excitable, i.e., the transmembrane potential exhibits a large deviation from its resting state value in the presence of a sufficiently strong signal, before eventually coming back to rest. Excitable cells such as neurons, cardiac myocytes, uterine muscle cells, etc. also share the property of having a refractory period after they are stimulated, during which time their response to a subsequent stimulus is significantly attenuated. In the PhD thesis, for which this is a pre-synopsis submission talk, we investigate the interaction between excitable and passive cells that are often present together in many different biological contexts. The heterogeneous electrical nature of the cellular assemblies (whose response to stimulus are qualitatively distinct) results in the coupled system exhibiting novel activity patterns of potential biological relevance that are absent in its constituent cells. Heterogeneity may also be organized spatially, whereby the relative density of passive cells can vary in different regions of an organ. Thus, we investigate how a gradient in passive cell density along a specific axis can organize the collective dynamical patterns of activity in such an organ. A possible consequence, such as in the uterus, would be the appearance of coordinated activation waves even in the absence of pacemaker cells. We also provide a generalisation of the result that interactions between excitable and passive cells can give rise to auto-rhythmicity. Further, we consider these coupled biological oscillators, whose period varies depending on the cellular micro-environment, and study the topological transition to vortex unbinding in these systems - specifically to understand the creation and destruction of self-sustaining rotating waves and their potential role in generating Braxton-Hicks contraction of the uterus.

(Pre-synopsis submission seminar)
Google Meet Link: meet.google.com/jre-wxku-sxx