The GluN2B-mediated fraction of the NMDAR EPSC is not significantly different between coronal and sagittal orientations. A) Whole-cell patch clamp recordings from CA1 pyramidal cells in either sagittal or coronal slices were made and the NMDAR EPSC was isolated at -40 mV in the presence of bicuculine (10 μM) and NBQX (5 μM). After a 10 minute stable baseline recording period at stimulation frequency 0.03 Hz, the GluN2B-selective antagonist Ro was applied for 40 minutes while stimulation continued. Scale bars represent 200 ms and 200 pA. B) The level of depression in the NMDAR EPSC induced by Ro, when quantified in the 40-50 minute epoch, was similar in sagittal and coronal slices. This indicates activation of a similar number of synaptic GluN2B-containing NMDARs during baseline synaptic stimulation in either slice orientation.