[Neuroscience] Izhikevich's Large Scale Mammalian Thalamocrotical model

[Fredo]

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_model_of_human_brain_support.pdf

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