(A–B) Representative confocal images showing vesicular glutamate transporter 1 (vGluT1)-immunoreactivity in the basolateral amygdala (BLA) from control (A) and PFFs-injected (B) mice. (C) Summarized data showing no change in the vGluT1 density in the BLA between control and PFFs-injected mice (control=27.5 ± 2 million/mm3, n=11 slices/3 mice; preformed fibrils (PFFs)=27.5 ± 3.8 million/mm3, n=12 slices/3 mice; p=0.98, MWU). (D–E) Representative traces of cortico-BLA excitatory postsynaptic currents (EPSCs) evoked by 20 Hz paired pulses of electric stimulation (D) and the summarized results of EPSC2/EPSC1 ratios (E, controls=1.45 ± 0.08, n=19 neurons/4 mice; PFFs=1.53 ± 0.13, n=18 neurons/4 mice; p=0.99, MWU). (F–G) Representative traces of cortico-BLA EPSCs evoked by 10 Hz paired pulses of optogenetic stimulation (F) and the summarized results of EPSC2/EPSC1 ratios (controls=0.64 ± 0.04, n=35 neurons/4 mice; PFFs=0.69 ± 0.07, n=31 neurons/4 mice; p=0.83, MWU). (H) Representative traces showing Sr2+ induced, optogenetically evoked EPSCs (Sr2+-EPSCs) at cortico-BLA synapses from control and PFFs-injected mice. Each open circle indicates a single identified Sr2+-EPSC. (I–J) Summarized result showing a reduction of the frequency (control=30.9 ± 4.3 Hz, n=24 neurons/3 mice; PFFs=18.9 ± 2.4 Hz, n=24 neurons/3 mice; p=0.012, MWU), but not the amplitude (control=19.2 ± 0.99 pA, n=24 neurons/3 mice; PFF=18.1 ± 0.98 pA, n=24 neurons/3 mice; p=0.31, MWU), of Sr2+-EPSCs at cortico-BLA synapses. (K) Representative cortico-BLA EPSC traces recorded at –80 mV and +40 mV from control and PFF-injected mice. Black dots indicate the time at which AMPA- and NMDA-mediated components were measured. (L) Summarized results showing a decreased AMPA/NMDA ratio at cortico-BLA synapses from PFFs-injected mice relative to controls (control=1.56 ± 0.13, n=20 neurons/3 mice; PFFs=1.03 ± 0.07, n=18 neurons/3 mice, p=0.0012, MWU). (M) Summarized results showing an increased AMPA receptor rectification index at cortico-BLA synapses from PFFs-injected mice relative to controls (control=1.74 ± 0.13, n=20 neurons/3 mice; PFFs=2.21 ± 0.18, n=18 neurons/3 mice, p=0.035, MWU). ns, not significant. * p<0.05.