Enhanced synaptic efficacy in the BLA neurons recruited into a fear memory trace is due to fear conditioning but not fear memory retrieval. A, Experimental procedure. B, Representative mEPSC traces recorded from dVenus+ and dVenus− neurons. C, D, dVenus+ neurons had a higher mEPSC frequency (C) and amplitude (D) than dVenus− neurons (n = 6 dVenus+ and 6 dVenus− neurons from 5 mice; frequency, paired t test, t(5) = 5.4, p = 0.0029; amplitude, t(5) = 7.8, p = 0.00056); **p < 0.01.