Synapse models and bufferIncomingSpikes

[RokasSt]

Hi Richard,

I have been working on some synapse class import to VERTEX and noticed that, for example, when there is a simple model of two cells and one synaptic connection with weight of 10nS the following method

function SM = bufferIncomingSpikes(SM, synIndeces, weightsToAdd)

  SM.gEventBuffer(synIndeces) = ...
   SM.gEventBuffer(synIndeces)  +weightsToAdd  ;
  end

correctly adds this weight; however, when I manually add 10 ( by replacing weightsToAdd in the sum with 10 or with the instantiated model attribute,for example, SM.gbase, that is equal to 10), this summation does not work and 10 is never added to SM.gEventBuffer.

Could you comment on this?

Thanks,
Best Wishes,
Rokas

@richardtomsett

[richardtomsett]

Hi @RokasSt, sorry for not replying sooner. So when you change bufferIncomingSpikes(SM, synIndeces, weightsToAdd) in SynapseModel_i_exp or SynapseModel_g_exp classes from doing

SM.gEventBuffer(synIndeces) = SM.gEventBuffer(synIndeces)  + weightsToAdd;

to

SM.gEventBuffer(synIndeces) = SM.gEventBuffer(synIndeces)  + 10;

it no longer works (i.e. that 10 is never actually added)? I'm not sure I understand why... bufferIncomingSpikes is called in the main simulation loop and adding a scalar to an array should just add the value of the scalar to all the specified indeces in the array. Weird. I'll try it out myself at some point and see if I can reproduce the problem...

[RokasSt]

Hi @richardtomsett ; not a big problem. Yes, the former one does not work:

SM.gEventBuffer(synIndeces) = SM.gEventBuffer(synIndeces) + weightsToAdd;
to

SM.gEventBuffer(synIndeces) = SM.gEventBuffer(synIndeces) + 10;

[richardtomsett]

Sorry just edited my comment after rereading your first one! That's strange. Not sure I'll get round to it till tomorrow but I'll try to reproduce the problem myself and debug from there. @RokasSt

[RokasSt]

Hi @richardtomsett ; thanks, that would be useful, if you can see whether you can reproduce this problem and fix it.

[richardtomsett]

Sorry it's taken me so long to look into this @RokasSt ! I think the issue might be happening if you are not setting the synaptic weights in the ConnectionParams structure or if you've set them to 0 (you might have done this as you were adding a weight directly in the SynapseModel class). VERTEX deletes any synapses with weight 0/without a weight at model initialisation, so the code you've changed to add 10 to the synaptic weight will never be called, as that synapse object will never actually be created. Does that make sense..?

To get around this, just make sure you set the weight parameter to a non-zero value in your ConnectionParams structure (unless this isn't compatible with your usage?).

If this isn't the issue then I'm stumped :\

[RokasSt]

Hi Richard,

Thank you for your response. Yes, we should be able to go around with specifying weight parameters to non-zero values every time we import a new model into VERTEX. I will look at this when I have time to come back to this project.

Best Regards,
Rokas
@richardtomsett