specific neurotransmitter receptor blockers demonstrates specificity of the responses and distinguish inhibitory (IPSC) from excitatory postsynaptic activity (EPSC). Sometimes, noise caused by fluctuation of membrane channels during the recording can cause membrane potential deflections that appear to be bewildering synaptic currents (Figure 4D1). Therefore, not every deviation from the baseline is mediated by synaptic transmission and cautious interpretation of the recorded traces is essential. The evaluation of presynaptic competence is in our view the most rigorous criteria of neuronal function but also the most difficult test. This requires either the culture of pure iN cells in a sufficient density or paired recordings. Finally, mature synapses also often show simple short-term plasticity such as depression or facilitation.
