53 / 88
49
New Biological Frontiers Illuminated by Molecular Sensors and Actuators
Poster Abstracts
15-POS
Board 15
Neural Influence on Synchronization of Cardiac Oscillators - A Computational Study
Krishnan Jayaraman
, Murugesh Sundaram T, Malathi Raman.
Annamalai University, Annamalai Nagar, India.
Biological rhythms, like the cardiac rhythm are often generated by large populations of mutually
interacting cellular oscillators. Typically individual oscillators in such populations have intrinsic
frequencies with a significant dispersion. The ability of such a population to generate a stable,
regulated rhythm depends critically on the nature of interactions among the oscillators. Although
the autorhythmic cells in the heart at a wide range of frequencies in culture, they beat at a
common frequency set by the sinus rhythm. Two nonlinear oscillators operating at different
frequencies can synchronize only under special conditions, which are expected to be more
stringent for a large network of oscillators with a range of intrinsic frequencies. Since the heart is
a large network of oscillators beating at a wide range of frequencies, synchronization is a serious
issue. The problem of synchronization in a grid model of cardiac cells with a considerable
gradient in intrinsic frequencies is investigated. Simulations involve the Demir model, which is
one among the detailed biophysical cardiac cell models. In the grid models there is a monotonic
variation in intrinsic frequency of cells along one of the diagonals, i.e. from the left-top corner to
the right-bottom corner. When the frequency range is of the order of the physiological range the
entire grid failed to synchronize to a common frequency even after prolonged simulation. It
points out the need for an external influence that can coax the cardiac oscillators to beat at a
single frequency. In order to achieve synchronization, a simple neural feedback system is
proposed in which neurons monitor the activities of cardiac cells and activate an entire “slower”
stretch of cells. For properly tuned feedback gain it is shown that synchronization can be
achieved within a short period.