Figure 4.

Effect of NMDA receptor antagonism in the amygdala on classical eye-blink conditioning. Percent CRs to the auditory CS (eye blinks that commenced 80 msec after CS onset) over 300 trials of training are shown for all 12 groups. The first set of four groups was injected with AP5 in the lateral/basolateral nucleus before stressor exposure (BLN/BEFORE). The second set was injected with AP5 in the lateral/basolateral nucleus after exposure to the stressor (BLN/AFTER). The third set was injected with AP5 into the central nucleus before stressor exposure (CN/BEFORE). Only NMDA receptor antagonism in the lateral/basolateral amygdaloid nucleus before stressor exposure prevented the stress-induced facilitation of associative learning 24 hr later. Bars: (Diagonal lines) Stress/AP5; (horizontal lines) no stress/AP5; (solid) stress/vehicle; (open) no stress/vehicle.