The model neuron consists of a single compartment with a membrane surface area of 29,000 µm2 and membrane capacitance (cm) of 1 uF/cm2. The Goldman-Hodgkin-Katz constant field equation is used in the computation of the leak, L- and T- currents. All other currents are computed using Ohm's law. The kinetics of most currents are scaled by temperature by means of Q10 values. The standard integration procedure uses a fixed time step (dt) of 50  µs, the variable time step method works as well. Descriptions of user-defined currents and membrane mechanisms are defined in so called mod files. You can create your own mod file with the NMODL description language. Note that after changing or creating a mod file you need to recompile the mod files. The following are the membrane mechanisms included in the Experiments section of MyFirstNEURON:
 
CURRENTS
MOD FILE
REFERENCE OBTAINED FROM
leak 
leak.mod
Huguenard, McCormick (1994)   
transient Na+
hh2.mod
McCormick, Huguenard (1992)  cortical pyramidal cells
delayed rectifier
hh2.mod
Huguenard, McCormick (1992)   
A-
ia.mod
Huguenard, McCormick (1992)  thalamic relay neurons
AHP-
iahp.mod
McCormick, Wang, Huguenard (1993)  bullfrog symp. ganglion cells
C-
ic.mod
Yamada, Koch, Adams (1989)  bullfrog symp. ganglion cells
L-
il.mod
McCormick, Huguenard (1992)  hippocampal pyramidal cells
M-
im.mod
Yamada, Koch, Adams (1989)  bullfrog symp. ganglion cells
T-
it.mod
Huguenard, McCormick (1992) thalamic relay neurons
OTHER
     
Ca2+ diffusion
cadyn.mod
McCormick, Huguenard (1992)  

The synaptic currents used in the tutorial are described in ampa, nmda, gabaA and gabaB mod files. These mod files are not in the proper format for network simulations.

Additional membrane mechanisms, including network-ready synapses with optional short-term plasticity, are available in the Create section:
 
persistent Na+
inap.mod
Golomb, Amitai (1997)  
action potential
hh3.mod
Traub, Miles (1991) hippocampal pyramidal cells
slow K+
iks.mod
Golomb, Amitai (1997)  
H-
ih. mod
Spain, Schwindt, Crill (1987)  cat sensorimotor cortex
AMPA
ampa.mod
   
GABAA
gabaA.mod
   

Calcium dynamics is modeled by a simple exponential decay in a thin shell underneath the membrane. Experimental data from thalamocortical cells indicate that action potentials and high-threshold calcium currents activate substantial calcium-activated potassium currents whereas low-threshold calcium currents do not. Therefore the T-current model does not update the internal calcium concentration.