[Neuroscience] Re: Ion channel distributions

Bill via neur-sci%40net.bio.net (by connelly.bill from gmail.com)
Sun Nov 30 03:01:06 EST 2008


Hi Rick

The short version is
1) No
2) Generally
3) Not especially

More complete version
1) Classical examples of varying ion channel distribution included the
high punctate density of voltage gated sodium channels at nodes of
ranvier along the axon, and high density calcium channels at
presynaptic terminals. Other exmaples are in the 1998/1999 papers by
Jeff Magee in J neurosci and Nature Neurosci showing the varying
density of Ih channels along the dendrites of CA1 cells to achieve
synaptic scaling of of EPSPs along the dendrite. There are all kinds
of varying concentration of ion channels along dendrites, and
dendrites vs axon. And of course a lot of the dendritic ion channels
are plastic. Again see papers my Jeff Magee, looking at the modulation
of A-type K channels

2) Generally speaking, absolutely. That's why Purkinje cells usually
tonically fire. Why Basket cells have a fast spiking phenotype and why
layer V dendrites have funny looking action potentials. Just like all
humans generally look like humans, but don't look identically. Neurons
that fall into one call generally behave very similarly. (Though don't
forget the effect passive membrane properties lend to neurons, i.e.
big cells are capacitive and have a slow response to membrane
currents)

3) Not especially
Have a wee look at Curr Opin Neurobiol. 1999 Jun;9(3):288-92 and Nat
Rev Neurosci. 2000 Dec;1(3):181-90.
On Nov 19, 3:47 am, Rick Giuly <rgiuly.gr... from yahoo.com> wrote:
> Hello All,
>
> I'm interested in modeling neurons and I have a few questions:
>
> (1) In adult animals, are ion channel distributions constant?
>
> (2) Do particular cell types have well defined ion channel
> distributions that are similar among all cells of the type? (For
> example does a Purkinje cell have a predictable ion channel
> distribution?)
>
> (3) Are the answers to questions (1) and (2) different for vertebrates
> and invertebrates?
>
> Any comments or paper recommendations are appreciated. I've done some
> literature searching and found some fragments of information on these
> topics but nothing definitive yet.
>
> -Rick



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