Proceedings of The Physiological Society
University of Oxford (2011) Proc Physiol Soc 23, PC168
Distributed control strategies for conductance regulation in dendrites
T. O'Leary1, D. J. Wyllie1
1. Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom.
A microscope image of a typical neurone points to an interesting logistical problem for mechanisms that regulate intrinsic membrane properties. Dendritic arbours are complex, with long, thin processes and varicosities that effectively compartmentalise biochemical and electrical signals. Distributions of membrane conductances therefore exert local effects as well as influencing the electrical properties in entire cells. Moreover, feedback signals representing the state of a particular location in a cell will only reflect local conditions. It is hard to imagine how regulatory control can be orchestrated centrally (at the soma, for example) such that the target intrinsic properties are satisfied in all compartments of the cell simultaneously, yet most existing models of activity-dependent regulation of intrinsic properties assume that changes are cell-wide and uniform within a cell . This problem, which has received a great deal of attention in the context of synaptic homeostasis , has not been not been extensively investigated in the context of homeostatic control of intrinsic properties . In this work we examine the effect local homeostatic mechanisms have on global intrinsic properties and on conductance distributions in dendrites using a multi-compartment conductance-based model. We find that simple rules can generate heterogeneous conductance distributions in morphologically reconstructed cells, and investigate the effect of noise on the performance of several biologically plausible homeostatic control mechanisms. Noise is found to distinguish the utility of different feedback control mechanisms (such as linear integral controllers and non-linear ‘bang-bang’ controllers) under simple assumptions, and this has important implications for the nature of biological homeostatic mechanisms that give rise to experimental data.
Where applicable, experiments conform with Society ethical requirements