Using ion_style() to treat eca as a fixed parameter and cai as a dynamical variable
Posted: Wed May 29, 2019 2:32 pm
I am porting Bazhenov's 2002 thalamocortical model of sleep-wake transitions (https://senselab.med.yale.edu/ModelDB/s ... 189#tabs-1) to NEURON. The model has a calcium current, as well as a calcium-dependent K+ current. As far as I can tell (I am trying to get the authors to respond on this point), they fix the calcium reversal potential (setting eca=140 mV), yet they allow the internal calcium concentration (cai) to vary. The model is written in C++, but cai's dynamics are based on a mod file (cadecay.mod) written by Destexhe (found here: https://senselab.med.yale.edu/ModelDB/S ... mod#tabs-2).
It seems strange to me to allow the internal calcium concentration to change while at the same time fixing eca, but I'm pretty sure that's what they did. (I may change this in my own model once I've successfully ported it, but I need to first replicate their results.) Here my questions:
1) Reading the documentation on ion_style() (https://www.neuron.yale.edu/neuron/stat ... /ions.html), it seems I should call h.ion_style("ca_ion",3, 1, 0, 0, 0, sec) , since I'm treating cai as a state variable, eca as a fixed parameter, and I don't want initialization or fadvance to change eca. Is this correct?
2) Within the mod file defining the calcium current, I assume I should place the line eca=140 (mV) within the PARAMETER (as opposed to the ASSIGNED) block...correct?
It seems strange to me to allow the internal calcium concentration to change while at the same time fixing eca, but I'm pretty sure that's what they did. (I may change this in my own model once I've successfully ported it, but I need to first replicate their results.) Here my questions:
1) Reading the documentation on ion_style() (https://www.neuron.yale.edu/neuron/stat ... /ions.html), it seems I should call h.ion_style("ca_ion",3, 1, 0, 0, 0, sec) , since I'm treating cai as a state variable, eca as a fixed parameter, and I don't want initialization or fadvance to change eca. Is this correct?
2) Within the mod file defining the calcium current, I assume I should place the line eca=140 (mV) within the PARAMETER (as opposed to the ASSIGNED) block...correct?