Auditory Fear Conditioning

“These viruses were microinjected into lateral amygdala, which is essential for auditory Pavlovian fear-conditioning. Histological staining with a GFP antibody revealed that ~20% of lateral amygdala neurons were transfected with either virus”

“Cannula placement was confirmed with crystal violet staining at the end of each experiment. Only those mice with bilateral placements in the basolateral complex of the amygdala were included in analysis”

“western blot analyses showed that HSV-CREB viral transfection increased CREB levels in the amygdala; Transfection with HSV-LacZ had no detectable effect on CREB expression”

“AL administration quickly and reversibly caused the membrane potential to become more negative (−5.9 ± 1.2 mV, t = 3.73, P < 0.01) in GFP + neurons, but had no effect on GFP − neighboring cells”

“both virus preparations were micro-infused bilaterally into the lateral amygdala ~3 days before tone fear conditioning”

“Memory for tone conditioning was assessed by measuring the percentage of time the mice spent freezing during a tone presentation conducted 24 h after conditioning. To test the impact of inactivating transfected neurons, AL (10 µM, 0.5 µl) or vehicle were infused bilaterally into the lateral amygdala ~30 min before the retrieval of auditory fear memory”

“we also infused AL or vehicle into the lateral amygdala of separate groups of mice and waited 4 h (instead of 30 min) before testing tone conditioning. Our results showed that AL infusion 4 h before testing had no effect on retrieval”

“we repeated the experiment just described, but this time added a second test 24 h after the first test. In the second test we reversed the treatments so that mice that got AL in the first test got VEH in the second test”

“we included an AL manipulation during both training and testing. Consistent with CREB's role in memory consolidation, we found that activation of the HSV-CREB neurons during training enhanced tone-associated fear memory (VEH/VEH, 70.0% ± 5.5%, n = 12); while inactivation of the HSV-CREB neurons with AL during training reduced tone-associated fear memory to control levels”

“we tested memory allocation 30 min after training, a time point known to precede memory consolidation. Indeed, when tested 30 min post-training, HSV-CREB mice did not show higher freezing than HSV-LacZ mice”

“we fear conditioned the mice before (and not after) viral injection. Then, we trained the same mice on taste aversion conditioning (CTA) 3 days following viral infection”

“we studied synaptic transmission and PPF in HSV-CREB neurons and non-transfected neighboring cells in the same slices in both naive and conditioned mice (24 hrs post-training)”

“we prepared acute lateral amygdala slices ~3 days after virus infusion and performed whole-cell recordings. We found that although HSV-CREB did not affect the resting membrane potential, input resistance, spike amplitude or the spike half-width of transfected lateral amygdala pyramidal neurons, it did significantly lower the AP threshold of those neurons”

“We measured the relationship between the EPSP slope and spike probability following different synaptic stimulation intensities”