I am trying to create the circuit in the image attached
I wrote the following code:

*Fitzhugh Nagumo
I1 0 1 PULSE(0 0.5mA 1NS 1NS 1NS 1NS 2ms)
L1 0 2 30H
R1 1 2 7500ohm
R2 1 0 3174ohm
C1 1 0 16.67nF
G1 1 0 value={-0.000037037*(v(1)**3)+0.00002167*(v(1)**2)}
.tran 0 10ms
.probe
.end

my problem is G1 isn't responding properly (it's giving me 0Amp) (and I think that because of that, also L1 and R1 are not working either)

can someone please help me?? THIS IS URGENT!!!

 

Try to build it up in LTspice as a schematic than trying to write the pspice code manually.

 

what is LTspice?
I tried to build the schematic in Orcad, the problem is I couldn't get the VCCS to send I=-0.000037037*v^3+0.00002167*v^2 (the gain can't be a variable)

 

This is what LTspice gives, and the netlist is
C1 c 0 16.67n
R1 c N001 7k5
L1 N001 0 30
R2 c 0 3k174
B1 0 c I=-3.7037e-5*(v(c)**3)+2.167e-5*(v(c)**2)
I1 0 c PULSE(0 0.5m 1n 1n 1n 1n 2m)
.tran 10m
.backanno
.end

Edit: I'm not familiar with Pspice, but can you designate a node simply as '1' ? In LTspice it would be 'N001' by default.

 

the graph is similar to what I got, but please check the current that comes out of the VCCS, it's not supposed to be 0 (also check the current on L1,R1)

 

please check the current that comes out of the VCCS, it's not supposed to be 0

The graph shows the current is not zero; it's peaking at 80fA. Granted, not much above zero , but the cap voltage which it's a function of is only 60uV peak.
I(L1) peaks at ~195pA.