Hi all,

I am a newbie in the field, not sure if this is the right place but:

I am researching if there are papers on SNNs that: a) model evolving connectivity (i.e. new connections, opposed to changing weights of existing what STDP does) and

b) model reward modulated STDP with long (reward) time delays (opposed to the <50ms as in the standard STDP literature).

Any feedback is greatly appreciated

Thxs Ben

asked Apr 02 '11 at 06:42

Ben's gravatar image

Ben
1223


2 Answers:

I thought i would answer my own question since I completed some research in the meantime:

Generally there are different versions of plasticity:

  • Hebbian/correlation based: STDP: temporal correlation

  • Homeostatic:

    • Synaptic scaling:scale all weights per synapse according to target firing rate Intrinsic plasticity: change the excitability of a synapse depending on postsynaptic firing (change the transfer function)

    • Short term plasticity: The release of neurotrasmitter is influenced by the recent firing history of the presynaptic neuron, on timescale of ms to minutes. In this way the synaptic transmission of dynamic synapses encodes not only the spike but also the history of previous spikes. In computational terms short term plasticity has been shown to implement a temporal filter (high or low-pass / increase or decrease of neurotransmitter release as response to a spike)

  • Structural plasticity: controversial, creation of new connections based on correlated firing patterns

  • Metaplasticity: Experience can change the plasticity rules themselves (!), e.g. regulating the balance of excitation and inhibition by altering the threshold for LTD/LTP. However, confusion in the literature on categorization though, needs still research to clarify

I found the following dissertation provides a good overview on this still young field: http://fias.uni-frankfurt.de/~savin/thesis.pdf

answered Sep 02 '11 at 05:25

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Ben
1223

Hi Ben, for your first point, I think you can take the network architecture to be the complete graph over all nodes and then you don't need to add new connections, you can simply block an edge by setting the weight high enough that it never gets used so, unless there's something very different about SNN architecture I don't know about, changing weights is enough. On the other question, as with most things SNN, I know nothing. However, a quick google search turned up this textbook, which seems to be reasonably recent (2002) and looks like it discusses both the questions you ask in the final few chapters.

answered Apr 08 '11 at 08:35

Bob%20Durrant's gravatar image

Bob Durrant
301410

thanks for the link, I knew the resource but rediscovered some useful materials. See also my answer to my own question for what i found out in the meantime.

(Sep 02 '11 at 05:27) Ben
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