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Subject:
From:
Johannes Bill <[log in to unmask]>
Reply To:
Spikey neuromorphic system - User <[log in to unmask]>
Date:
Thu, 10 Nov 2016 11:44:57 +0100
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Dear Rolandas,

Maybe this is really more a "pyNN" question than a "hardware" question. 
Typically, a SpikeSourceArray is not "a neuron that spikes"; rather it 
is an abstract object that generates spike events at predefined spike times.

In the case of the Spikey chip, these spikes are fed into the system at 
the predefined spike times via a subset of synapse drivers. The first 
SpikeSourceArray generated in the pynn script will send its spikes 
through driver no. 255 (resp 511), the second SpikeSourceArray will use 
driver 254 (resp 510),... For the numbering please see
https://electronicvisions.github.io/hbp-sp9-guidebook/pm/spikey/spikey_school.html#introduction-to-the-hardware-system

With this in mind, I must admit that I don't fully understand your question:

"I want to create a network of let's say 100 neurons connected all to 
all, that gets input from other 10 neurons. Now, from time to time I 
want to use different 10 neurons (to train different patterns). The 
question is, how to address which 10 neurons on the chip to take?"

Maybe what you have in mind are more than 10 "other neurons"? Are these 
maybe multiple populations, each of size 10? Are these inputs 
full-fledged neurons that have a membrane potential, reversal 
potentials, etc.? Or is their only distinct property their spike time? 
In this case, maybe you could generate multiple populations of 
SpikeSourceArray's, and let only one of the populations fire per 
training epoch?

Are these ideas pointing in the right direction? Otherwise I can offer 
that you send me a sketch of your network architecture, or a minimal 
pyNN script that works properly in NEST. Maybe this can help to shed 
light on this matter.

Best regards,
Johannes



On 11/09/2016 11:48 PM, SUBSCRIBE KIP-SPIKEY-USERS Anonymous wrote:
> Dear Johannes,
>
> thanks for your response.
>
> It is probably that I don't understand something very simple. My problem is that I want to create a network of let's say 100 neurons connected all to all, that gets input from other 10 neurons. Now, from time to time I want to use different 10 neurons (to train different patterns). The question is, how to address which 10 neurons on the chip to take?
>
> In something like this:
>
> pInput = pynn.Population(10, pynn.SpikeSourceArray, {'spike_times': np.arange(ststart, simtime, ststep)}, label="input")
> pCausal = pynn.Population(100, pynn.IF_facets_hardware1, neuronParams) #Integrate-and-fire model for use with the FACETS hardware
> ...
> connection_method = pynn.AllToAllConnector(weights=7*wemin)
> prjCausal = pynn.Projection(pInput, pCausal, method=connection_method, target='excitatory', synapse_dynamics=pynn.SynapseDynamics(slow=stdp_model))
>
> I'm not sure which 10 neurons on the chip it is using and how to pick other 10?
>
> Hope that my questions make sense.
>
> Thanks,
> Rolandas
>
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