Figure 3.

Fear conditioning reduces the balance of inhibition to excitation in the PL-amygdala pathway. A, Hypothetical model of glutamatergic excitation and local feedforward inhibition in principal neurons resulting from optic stimulation of IL or PL BLA terminals onto interneurons (IN) or principal neurons (PN). B, Representative biphasic EPSC-IPSCs evoked by optic stimulation (5 ms, 460 nm) of IL or PL terminals with postsynaptic neuron clamped at −50 mV. Calibration: 300 pA × 40 ms. C, Mean amplitude ratio of I:E ratio as a function of training. D, Distribution of component amplitudes for individual neurons during PL stimulation. *p < 0.05, two-tailed t test [IL n = 10 (5) naive, 7 (6) trained; PL n = 8 (7) naive, 15 (9) trained].