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[Neuroscience] Re: Izhikevich's Large Scale Mammalian Thalamocrotical model

J.A.Legris via neur-sci%40net.bio.net (by jalegris from sympatico.ca)
Tue Oct 7 09:10:56 EST 2008

On Sep 29, 10:57 am, "Fredo" <fr... from hotmail.com> wrote:
> I'm trying to implement something like Eugene Izhikevich's model described
> in "A Large-Scale Model of Mammalian Thalamocortical Systems", but I've run
> into an issue I can't quite figure out.
> From the Supporting Information:http://vesicle.nsi.edu/users/izhikevich/publications/large-scale_mode...
> On page 8, he describes the current used in the equation on page 7 as:
> I(t) = -Idendr - Isyn
> Then below, he provides the equation for calculating Idendr per compartment.
> He says in the text that the somatic and terminal dendritic compartments all
> have a value of 0 of Idendr.
> So my question is, in I(t) = -Idendr - Isyn
> What is Idendr? Is it the sum of Idendr for the compartments attached to the
> somatic compartment? The sum of all Idendr for all compartments? or
> something else?
> Does anyone know?
> Thanks

Sorry, my first attempt at this reply was mangled.

On page 8 at the end of section 2.1 he writes:

"Each neuron has a somatic compartment and a set of dendritic
compartments. The number of dendritic
compartments of a neuron in each cortical layer is at least S*scale/M
where S is the number of synapses
the neuron receives in the layer (see Fig. 9), scale= 0.05 is the
scale-down factor when we simulate fewer
than 10^11 neurons, and the parameter M = 40 is the maximal number of
synapses per compartment.
The dendritic current at each compartment consists of the currents
coming from the down ("mother")
compartment (zero for somatic compartments) and up ("daughter")
compartments (zero for terminal

Idendr = Gdown (V - Vdown ) + SUM[up] Gup (V - Vup)"

Observe that he does not say "the somatic and terminal dendritic
compartments all have a value of 0 of Idendr". He says that the
contribution to Idendr from the down ("mother") compartment is zero
for somatic compartments and that the contribution to Idendr from the
up ("daughter") compartments is zero for terminal compartments.

In other words:

Idendr[somatic] = SUM[up] Gup (V - Vup)
Idendr[terminal] = Gdown (V - Vdown )


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