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Roles of IA and morphology in action potential propagation in CA1 pyramidal cell dendrites
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Roles of I A and morphology in action potential propagation in CA1 pyramidal cell dendrites
Corey D. Acker1, 3 and John A. White2, 3
| (1) |
Department of Neuroscience, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, CT 06030, USA |
| (2) |
Department of Biomedical Engineering, Boston University, 44 Cummington St., Boston, MA 02215, USA |
| (3) |
Department of Biomedical Engineering, Center for BioDynamics, and Center for Memory and Brain, Boston University, Boston, MA, USA |
Received: 4 July 2006 Revised: 21 January 2007 Accepted: 8 March 2007 Published online: 20 April 2007
Abstract Dendrites of CA1 pyramidal cells of the hippocampus, along with those of a wide range of other cell types, support active
backpropagation of axonal action potentials. Consistent with previous work, recent experiments demonstrating that properties
of synaptic plasticity are different for distal synapses, suggest an important functional role of bAPs, which are known to
be prone to failure in distal locations. Using conductance-based models of CA1 pyramidal cells, we show that underlying “traveling
wave attractors” control action potential propagation in the apical dendrites. By computing these attractors, we dissect and
quantify the effects of I A channels and dendritic morphology on bAP amplitudes. We find that non-uniform activation properties of I A can lead to backpropagation failure similar to that observed experimentally in these cells. Amplitude of forward propagation
of dendritic spikes also depends strongly on the activation dynamics of I A. I A channel properties also influence transients at dendritic branch points and whether or not propagation failure results. The
branching pattern in the distal apical dendrites, combined with I A channel properties in this region, ensure propagation failure in the apical tuft for a large range of I A conductance densities. At the same time, these same properties ensure failure of forward propagating dendritic spikes initiated
in the distal tuft in the absence of some form of cooperativity of synaptic activation.
Electronic supplemary material The online version of this article (doi:10.1007/s10827-007-0028-8) contains supplementary material, which is available to authorized users.
Keywords Backpropagation - Propagation failure - Traveling wave attractor - bAP - Dendritic spike
Action Editor: Alain Destexhe
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