Analysis of voltage dependent sensitivity of synaptic NMDA receptors to 100 μM Mg2+ in lamina II interneurons. A, Representative traces of focal stimulation evoked NMDA-EPSCs recorded at different holding potentials (-90 mV to +50 mV at 20 mV increment). B, Current - voltage relationship of NMDA EPSCs shown in A. The reversal potential for this example neuron is 0 mV. C shows that synaptic NMDA EPSCs from EGFP+ (n = 18) and EGFP- (n = 19) neurons have similar g(-90 mV)/g(MIC) that are comparable to the value of NMDA receptors with NR2A/B subunits. Perforated lines indicate the conductance ratio of NR2A/B or NR2C/D receptor induced currents derived from oocyte expression data.