-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hello Thomas, thank you for your reply and sorry for my late answer. I already performed the experiments I described here last week, but had no time to reply until now. > In particular, the parameters drvifall (affects the time > constant and synaptic weight; this parameter first, because it is > more sensitive) and drviout (affects mostly the synaptic weight) > are adjusted until a target rate of the postsynaptic neurons is > reached. As these parameters can be configured only row-wise for > synapses, firing rates are averaged across all hardware neurons > during calibration. Due to this protocol, synapses are > calibrated to generate EPSPs with comparable impact on the firing > rates of postsynaptic neurons (i.e. area under EPSP), but not > necessarily with comparable time constants. Ok, so as far as I understand it the LIF parameters "w" (synaptic weight) and "tauM" (membrane time constant with tauM = cM / gL) influence the hidden "tauE" (excitatory synapse time constant) parameter. That's also what some quick experiments on the hardware showed. So in case "tauM" and "w" stay fixed I can calculate "tauE" and adapt the other parameters (e.g. threshold and leak potential "eL"/"eTh") without implicitly changing "tauE". That's enough for me. > As it is difficult to extract the synaptic time constant from the > membrane potential, we can not provide you with numbers on how > correlated time constants and area under EPSPs are. Well, that turns out to be really simple: The estimation of tauE from a membrane potential trace is a matter of few seconds. I've simply hooked my (rather naive) Downhill-Simplex implementation onto my high-speed single-neuron AdEx integrator and defined the RMSE between simulated and reference membrane potential trace as cost function. See attachment for the results. In case you're interested: I'll publish the source code in December. Again, thank you for your answer and best wishes from the not-so-far-away Kirchheimbolanden, Andreas -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQEcBAEBAgAGBQJWOc0SAAoJEGiL9AshMiPd0BQH/1WfTlSgll4dlx8nIdx4tMVV QSGnTy/gZBxiafKutIwEjxM0eXo6FPhs3EaM3MtWMRUFsW99QcerWf39osrxFJhK w/5PgIUmzfkkMiBh/yVJb2l4LHiRURbbK/VcLmW8v6TgfLRvpzrheqUGhUaIngKq Cbo6+3diX+dUr7kYc0ZWZmAVFLEGchzT/9LmZ+uFiE6Izwgge97Q0fFd/wj+cWLu HoFJjB8Er5GCkWWGCQRnW5Kr4UTzS99dgbUogjE+4LqcO76Q6V+hJEqgyFRIiCQs jAN9cNY13VKcbIdv8u5wJIBJM82W4KU/BFis7lsMn24faGyNenEEMgu7/x9vUVg= =29Wd -----END PGP SIGNATURE----- ######################################################################## To unsubscribe from the KIP-SPIKEY-USERS list, click the following link: https://listserv.uni-heidelberg.de/cgi-bin/wa?SUBED1=KIP-SPIKEY-USERS