Fig. 1.
Postsynaptic calcium triggers IC LTP. (a) Brain diagram of adult mouse IC. (b) Top: sample traces show input-output relationship of AMPA receptor-mediated EPSCs in the IC. Bottom: Plots of input-output curve in WT mice IC (n = 8 neurons/5 mice). (c) The evoked EPSC was completely blocked by CNQX (20 μM). (d) A scheme illustrating the pairing protocol consisting of pairing 80 presynaptic pulses at 2 Hz with postsynaptic depolarization (holding at + 30 mV). (e) Sample traces at the indicated time points are shown above the plot. Top: sample traces of EPSCs with single-pulse stimulation during baseline (1) and 60 min after pairing protocol (2) at a holding membrane potential of −60 mV. (f) Pooled data to illustrate the time course of LTP (black, n = 14/12) and control (white, n = 11/11). There is significant difference between LTP and control (two-way ANOVA, F1,46 = 70.52, ***p < 0.001). (g) Bath application of AP-5 (50 μM) completely blocked the induction of LTP in one neuron. (h) Pooled data of AP-5 (n = 5 neurons/4 mice). (i) Postsynaptic application of BAPTA (20 mM in the recording pipette) completely blocked the induction of LTP in one neuron. (j) Pooled data of BAPTA (n = 5/4). (k) Summary of AP-5 and BAPTA on the induction of LTP. The amplitudes of EPSCs in AP-5 or BAPTA were significantly decreased compared with LTP (one-way ANOVA, F2,21 = 14.17, ***p < 0.001). Calibration, 50 pA, 50 ms. The mean amplitudes of EPSCs were determined at 50–60 min after pairing protocol. The arrow donates the time of pairing protocol. Error bars represent SEM; ***p < 0.001.