Abstract
Introduction
Although the autorhythmic cells in the heart beat at a wide range of frequencies (80–15 bpm) in culture, in the whole heart they beat at a common frequency set by the normal 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. In this paper we investigate this problem using simulations involving Noble cardiac cell model.
Methods and Materials
We conducted two sets of simulations. The first set involves cell-pair models of cardiac cells using the well-known Noble cell model, with and without neural feedback. The second set of experiments involves grid models of Noble cells with corner-to-corner variation of intrinsic frequencies.
External input, representing neural influence, is presented at varied locations and is adjusted to produce best synchronization.
Observations
Cardiac Cell pair without neural feedback: Lower resistance of coupling and lesser discrepancy in intrinsic frequencies improve synchronization.
Innervated Cell Pair
A pair of cells that otherwise do not synchronize are made to synchronize by appropriate neural feedback.
Grid of Cardiac Cells without neural feedback
Synchronization took longer with increasing frequency range and was never complete.
Innervated Grid of cardiac cells
Improved synchronization was achieved by neural feedback applied at specific locations in the grid. Input location and feedback gain are crucial for obtaining rapid synchronization.
Conclusion
Neural feedback seems to play a crucial role in forging the activities of cardiac oscillators to a unitary rhythm.
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Krishnan, J., Chakravarthy, V.S., Radhakrishnan, S. et al. Neural influence is essential for synchronizing cardiac oscillators: A computational model. Indian J Thorac Cardiovasc Surg 21, 262–268 (2005). https://doi.org/10.1007/s12055-005-0003-9
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DOI: https://doi.org/10.1007/s12055-005-0003-9