The HH model certainly does still serve as the basis for more sophisticated
current models. For example, see Neuron at http://neuron.duke.edu/. The
"Users Manual" has a page on a "Brief History of Computational
Neurosciences".
The m^3h and n^4 terms were selected to best represent the actual
experimental
data. The could be expected to result from multiple single-unit (first
order diff-eqs)
interacting which seems to be just what ion channels are.
In any event, any model of nerve cells must model the voltage dependent of
the
probability of ion channel opening and closing (and inactivating). And that
is exactly
what the alpha and beta vs V terms for m, n, and h do. So "more modern"
models
simply add ways to put in your own favorite ion channel dynamics.
"Edmund Müller" <edmund.mueller at freenet.de> wrote in message
news:a1ufmv$t8j0k$1 at ID-9504.news.dfncis.de...
> Hi NG,
>> in some computer simulation we use the HH model as described in
>> Hodgkin, A. L. and A.F. Huxley. 1952d. A quantitive description of
membrane
> current and its application to conduction and excitation in nerve. J.
> Physiol. (Lond.) 117: 500-544.
>> Well, this is half a century old. I wonder it in the mean time other
models
> were tried and published or the model was modified and improved.
>> They themselves mentioned for example, that the "curve fitting" might have
> been improved by using higher exponents of n They used n^4 to reduce the
> computational effort, quite understandable at those times, I think.
Nowadays
> computational power is manyfold. So maybe somebody has tried the
suggestion?
>> What about the knowledge of the assumption of "valves" (probabilitiy of
> being open: n, m, h in HH) in channnel proteins today. Is it still valid,
> e.g. potassium channels having four particles of which all must be in a
> certain position to open it (n^4), and 3 similar and one different for
> natrium channels? Or are the numbers different? And is it the same in rat
> hippocampal neurons?
>> Sorry for the lots of question, but I'm actually a foreigner to
> neurophysiology who touched the topic from a technical side.
> Interdisciplinary work can sometimes be hard ...
>> Edmund
>>>>