Update model documentation for iaf_psc_delta model

[ackurth]

No description provided.

[heplesser]

This looks quite good, see small comments inline.

But it made me also wonder about the units of i_syn, also in the other iaf_psc models. We need to take a look at that.

[heplesser]

This looks quite good, see small comments inline.

But it made me also wonder about the units of i_syn, also in the other iaf_psc models. We need to take a look at that.

@ackurth I looked more closely at this (also for the alpha case) and the situation is as follows:

• We need to provide information on the unit of $w_j$
• For the delta synapse, is the unit of $w_j$ actually pA or is it rather mV? I'm a bit confused here. This is, I guess related to the question if the membrane potential upon a delta spike input should jump by $w_j$ (which is does at present) or by $w_j/C_m$
• For all other psc synapses, the connection weight $w_j$ is always interpreted in pA, which means that $i_{syn}$ is dimensionless. Then, in the equations for "The individual post-synaptic currents (PSCs) are given by" and "the total charge transferred", we should always look at $w_j \times i_{syn}$ to that units work out.

What do you think?

[ackurth]

I reformulated now trying to avoid the unit issue but to be very explicit regarding what is going on.
Please have a look.
If you don't like it this way I will alter it according to what you requested above.

[heplesser]

I reformulated now trying to avoid the unit issue but to be very explicit regarding what is going on. Please have a look. If you don't like it this way I will alter it according to what you requested above.

This looks much better now. But I find the $\Delta \dot{V}{syn}$ a bit difficult to read. How about just $\dot{Delta}{syn}$?

Concerning $i_{syn}$ and $q$, they now have the units A/V and F, respectively. I think it would make more sense to include $w$ to the equations so we end up with A and F (i.e., pA and pF).

It would also be good to extend "where is the corresponding synaptic weight." to "where is the corresponding synaptic weight in mV."

[ackurth]

This looks much better now. But I find the $\Delta \dot{V}{syn}$ a bit difficult to read. How about just $\dot{Delta}{syn}$?
Done

Concerning isyn and q, they now have the units A/V and F, respectively. I think it would make more sense to include w to the equations so we end up with A and F (i.e., pA and pF).

It would also be good to extend "where is the corresponding synaptic weight." to "where is the corresponding synaptic weight in mV."

The units should be consistent now, please check.

[heplesser]

@ackurth Nice, thanks!

[heplesser]

@ackurth There seems to be a line break missing, making the copyright-checker unhappy:

[COPY] models/iaf_psc_delta.h: expected ' *  iaf_psc_delta.h', found ' *  iaf_psc_delta.h This file is part of NEST.'.

[clinssen]

OK, this looks fine. Many thanks!