Fig. 3.

Layer IV excitatory neurons of the barrel cortex lack N-methyl-d-aspartate receptor (NMDAR)-mediated postsynaptic responses in CxNR1KO mice. A: in control mice, layer IV excitatory neurons respond to membrane depolarization with an adapting train of spikes (regular spike). C: at a holding potential (H.P.) of +60-mV, stimulation of the VPM induces excitatory postsynaptic current (EPSC) with a longer duration, whereas at −70 mV it has a short duration, indicating that the EPSC is mediated by AMPA receptors (AMPARs) and NMDARs. E: at +60 mV, the EPSC is partially blocked by application of an NMDAR antagonist, d-APV (100 μM; trace 1, before; trace 2, after d-APV). To see the temporal difference between AMPAR-mediated EPSC and NMDAR-mediated (d-APV-sensitive) current, we show the record at a faster sweep speed. B: in CxNR1KO mice, layer IV excitatory neurons also fire regular spikes. D: the EPSCs induced from stimulation of VPM have similar durations at different holding potentials. F: the EPSC at +60 mV is completely blocked by AMPAR antagonist NBQX (10 μM, trace 1, before; trace 2, after NBQX, also at a faster sweep speed). G: in control mice, the averaged half-amplitude duration of EPSCs at +60 mV is 159.7 ± 14.0 ms (n = 15), whereas that in CxNR1KO mice is 79.6 ± 10.4 ms, which is significantly shorter (P < 0.0003) than control mice.