[NEST Users] Inhibitory plasticity with current based neurons

Dear all, I would like to simulate a network of current based LIF ('iaf_psc_delta') with inhibitory plasticity. I tried using the model vogels_sprekeler_synapse, but the resulting weights are positive (and they increase when firing rate is high). I guess it is because when used with conductance based neurons, the resulting weights would be multiplied by a gI<0? And with current based neurons, this is not the case. The weight is directly used as the synaptic weight. Do I understand it right? Is there a way to implement inhibitory plasticity using the vogels_sprekeler_synapse and current based LIF? Best, Júlia