John Walmsley

Doctoral Student

Research Assistant

Student, Balliol College

Wolfson Building, Parks Road, Oxford OX1 3QD

Interests

I am a DPhil student in the Computational Biology group working on computational cardiac electrophysiology. My research is focussed on novel methods for incorporating heterogeneity and variability observed in experimental data into computational models of the cardiac action potential. I am using two approaches, phenomenological modelling and populations of biophysically detailed models. My research has three main topics:

Isolated cardiac myocytes demonstrate a beat-to-beat variability in their action potential duration. To what extent does this phenomena translate to a tissue level? I have developed a phenomenological model of the action potential capable of accurately reproducing beat-to-beat variability recorded from isolated cardiac myocytes. This can then be simulated in tissue using Chaste, revealing a marked reduction in beat-to-beat variability.
Optical mapping of human left ventricular wedge preparations reveals heterogeneity in action potential duration across the wall of the heart. However, coupling in cardiac electrophysiology simulations tends to remove this heterogeneity. Using Chaste and the OeRC cluster, I am optimising the parameters of a phenomenological model in tissue to construct heterogeneous action potential models of individual experiments.
Electrophysiological changes occur during heart failure in humans, and recent studies have demonstrated changes in mRNA expression levels between failing and non-failing hearts. I am using a population based approach to investigate how variation between patients may influence biomarkers of arrhythmogenic risk.

I also have research interests in the following areas; sensitivity analysis, stochastic simulation, modelling and simulation software, standardisation and interoperability of electrophysiology models, high performance computing, validation of models and meaningful comparison to experimental data, and philosophy of systems biology.

I am currently collaborating with Prof. Igor Efimov on the modelling of heart failure in humans.