[NEST Users] Collect the calcium concentration of the neuron without structural plasticity

Dear NEST Users, I would like to "record" or read calcium concentration of the neurons (let's say aeif_cond_exp). For now Ca variable is 0 before and after I simulate, however the neuron spikes. Is there any neuron model that supports this, or do I need to edit the nestml of the desired model to achieve this. If so, a sample code snippet would be helpful. -- Thanks and Regards *Maryada*