Figure 2.
Synaptic properties recorded in CA1 and CA2 neurons. Excitatory synaptic currents in response to electrical stimulation were not significantly different between CA2 and CA1 neurons. A, A range of stimulation intensities up to 60 mA stimulation were used to evoke synaptic responses recorded in CA1 (black diamonds) and CA2 neurons (white squares). At no intensity were the two significantly different (n = 8 cells each). B, The level of PPF was determined by delivering two electrical pulses at varying intervals. The ratio of the amplitude of the second response to the amplitude of the first response is plotted according to the interval between the two pulses. PPF in CA2 was very similar to PPF in CA1, but was larger at the smallest interval (*p < 0.03; n = 10 cells each). C, mEPSCs did not differ between CA1 and CA2. Shown are example traces, NMDA/AMPA ratios, and frequency of events (n = 9 neurons each). Calibration: 10 pA, 100 ms. D, Representative NMDA receptor currents from CA1 and CA2 neurons, recorded at +40 mV. Calibration: 20 pA (CA1) and 10 pA (CA2), 25 ms. NMDA receptor-dependent current amplitudes did not differ significantly between CA1 and CA2 at several stimulation intensities (n = 10 in each case; p > 0.2 at all stimulation intensities, t test). Error bars indicate SEM.