".. We
carried out multi-site voltage-sensitive dye imaging of membrane potential transients from thin basal
branches of prefrontal cortical pyramidal neurons before and after application of channel blockers. We
found that backpropagating action potentials (bAPs) are predominantly controlled by voltage-gated
sodium and A-type potassium channels. In contrast, pharmacologically blocking the delayed rectifier
potassium, voltage-gated calcium or Ih, conductance had little effect on dendritic action potential
propagation. Optically recorded bAP waveforms were quantified and multicompartmental modeling
(NEURON) was used to link the observed behavior with the underlying biophysical properties. The
best-fit model included a non-uniform sodium channel distribution with decreasing conductance with
distance from the soma, together with a non-uniform (increasing) A-type potassium conductance. AP
amplitudes decline with distance in this model, but to a lesser extent than previously thought. We used
this model to explore the mechanisms underlying two sets of published data involving high frequency
trains of action potentials, and the local generation of sodium spikelets. ..."
Reference:
1 .
Acker CD, Antic SD (2009) Quantitative assessment of the distributions of membrane conductances involved in action potential backpropagation along basal dendrites. J Neurophysiol 101:1524-41 [PubMed]
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