Figure 2

From: Observation of Distressed Conspecific as a Model of Emotional Trauma Generates Silent Synapses in the Prefrontal-Amygdala Pathway and Enhances Fear Learning, but Ketamine Abolishes those Effects

Figure 2

OF, but not other forms of stress, decreases AMPAR/NMDAR current ratio in dmPFC–BLA synapses (a) Example images of ChR2-Venus AAV injection site and recording site. Left: A tiled fluorescent image of dmPFC. Middle: A tiled confocal image of BLA from the same animal, dotted white lines mark positions of the external capsule (left) and the internal capsule (right). Right: A magnified image of ChR2-Venus expressing fibers within the dotted square. (b) Left: examples of AMPAR (lower) and AMPAR/NMDAR mixed currents (upper) in neurons from a control mouse (left) and an OF mouse (right). Averages of 10 consecutive sweeps (gray) are shown in black. Vertical black bars illustrate reading of each current. Right: AMPAR/NMDAR indices for BLA inputs from dmPFC (left) or TeA (right) in each behavioral group: control (white), OF (black), auditory fear conditioning (gray), and immobilization (gradient). (c) Left: examples of the mixed AMPAR- and NMDAR-mediated currents recorded at +40 mV, NMDAR currents isolated in the presence of 20 μM CNQX and AMPAR-traces obtained by digital subtraction of the NMDAR trace from the mixed trace. Right: AMPAR/NMDAR ratios for BLA inputs from dmPFC in control (white) OF (black) groups. (d) Left: examples of pharmacologically isolated EPSCs evoked at holding potentials ranging from −77 to +43 mV for AMPAR (top) and from −82 to +38 for NMDAR (bottom) at a step of 20 mV. Right: averaged current–voltage plots of the AMPAR (top) and NMDAR (bottom) currents in control (gray symbols), and OF (black symbols) groups. Current values are normalized to those at −77 mV and +38 mV membrane potential for AMPAR and NMDAR, respectively. Data are presented as mean±SEM. Number of cells (upper) and animals (lower) are shown. *p<0.05, **p<0.01. BLA, basolateral amygdala; dmPFC, dorsomedial prefrontal cortex; OF, observational fear.