Publication Date:
2022-05-26
Description:
Author Posting. © The Authors, 2010. This is the author's version of the work. It is posted here by permission of Nature Publishing Group for personal use, not for redistribution. The definitive version was published in Nature Neuroscience 13 (2010): 852-860, doi:10.1038/nn.2574.
Description:
In cortical pyramidal neurons, the axon initial segment (AIS) plays a pivotal role in synaptic
integration. It has been asserted that this property reflects a high density of Na+ channels in AIS.
However, we here report that AP–associated Na+ flux, as measured by high–speed fluorescence
Na+ imaging, is about 3 times larger in the rat AIS than in the soma. Spike evoked Na+ flux in
the AIS and the first node of Ranvier is about the same, and in the basal dendrites it is about 8
times lower. At near threshold voltages persistent Na+ conductance is almost entirely axonal.
Finally, we report that on a time scale of seconds, passive diffusion and not pumping is
responsible for maintaining transmembrane Na+ gradients in thin axons during high frequency
AP firing. In computer simulations, these data were consistent with the known features of AP
generation in these neurons.
Description:
Supported by US–
Israel BSF Grant (2003082), Grass Faculty Grant from the MBL, NIH Grant (NS16295),
Multiple Sclerosis Society Grant (PP1367), and a fellowship from the Gruss Lipper Foundation.
Repository Name:
Woods Hole Open Access Server
Type:
Preprint
Format:
application/pdf
Format:
video/mpeg
Format:
video/wmv
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