Hi Anthony,

Thank you for writing in. This phenomenon is probably the result of an internal optimization that NEST carries out: the synaptic weight is only ever actually updated when a synapse receives a presynaptic spike. At that time, the updated weight is needed so that the postsynaptic potential has the right amplitude. However, postsynaptic spikes are buffered and not immediately processed into a weight update, because the updated weight is not yet needed at the time of the post spike (there is no synaptic transmission occurring in that case).

To amend this, try to insert a "dummy" presynaptic spike at the very end of your simulation. It should be far away from other spikes to as to not change the weight too much, but it will trigger the weight update due to the previous (buffered) postsynaptic spike.

Please see the NESTML STDP windows tutorial (https://nestml.readthedocs.io/en/latest/tutorials/stdp_windows/stdp_windows....) for a full example.

Hope this helps!

All the best, Charl

On Mon, Oct 2, 2023, at 00:23, Tony Lee wrote:

Hi,

I'm attempting to recreate the STDP dynamic figure like that of [this figure](https://www.jneurosci.org/content/jneuro/20/23/8812/F1.large.jpg?width=800&a...) (from [this paper](https://www.jneurosci.org/content/20/23/8812)).

However, no matter how I tune the time-constants and transmission delays, it seems that the potentiation side of the dynamics is just missing. I've checked the NEST ML equations and C++ header files and they look fine.

Thus, I am needing a second opinion to see if I am missing something obvious. [Here](https://gist.github.com/aoot/9409b939e891a1c823cc7defe97ab479) is the code in ipynb form and the figure I have (missing the LTP side).

Thank you, Anthony _______________________________________________ NEST Users mailing list -- users@nest-simulator.org To unsubscribe send an email to users-leave@nest-simulator.org