Figure 1.

Tetanic stimulation of the parabrachial input induces LTP at the synapses onto CeAL neurons A, average normalized EPSC amplitude plotted against time for 14 neurons before and after tetanic stimulation of the medial input (•) and a control input from the BLA (^) that was not tetanized. The inputs were stimulated with paired pulses with an interpulse interval of 50 ms. Representative EPSCs from the indicated time points are shown in B for the tetanized input (upper traces) and the control input (lower traces). C, the average normalized paired-pulse ratios for the same cells shown in A are plotted against time. There is an increase in release probability with LTP as shown by the reduction in paired-pulse ratio. EPSCs from the input showing LTP have been normalized to the first EPSC and overlaid in D to illustrate the change in paired-pulse ratio during LTP.