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. Author manuscript; available in PMC: 2017 Sep 5.
Published in final edited form as: Science. 2015 May 28;348(6238):1007–1013. doi: 10.1126/science.aaa5542

Figure 3. Recovery of Memory from Amnesia under a Variety of Conditions.

Figure 3

(A) DG engram activation and optogenetic place avoidance (OptoPA). During habituation neither group displayed significant avoidance of target zone. For Natural Recall the ANI group (n = 10) displayed significantly less freezing than SAL group (n = 12) in Context B (p < 0.005). SAL and ANI displayed similar levels of OptoPA.

(B) CA1 engram activation and CFC. 1 day post-CFC (Test 1) ANI group (n = 9) displayed significantly less freezing than SAL group (n = 10) in Context B (p < 0.01). 2 days post-training (Engram Activation), light-activation of CA1 engrams elicited freezing in both SAL (p < 0.01) and ANI groups (p < 0.001). 3 days post-training (Test 2) ANI group froze less than SAL group in Context B (p < 0.01).

(C) Lateral amygdala (LA) engram activation and tone fear conditioning (TFC). The behavioral schedule was identical to that in Fig. 3B, except that context tests were replaced with tone tests in Context C (Materials and Methods). (Left) example image of ChR2-mCherry labeling of LA neurons. 2% of DAPI cells were labeled by ChR2. (Right) 1 day post-training (Test 1), ANI group (n = 9) displayed significantly less freezing to tone than SAL group (n = 9) (p < 0.05). 2 days post-training (Engram Activation), significant light-induced freezing was observed for both SAL (p < 0.005) and ANI groups (p < 0.005). 3 days post-training (Test 2) ANI group froze less to tone than SAL group (p < 0.05).

(D) DG engram activation and CFC reconsolidation. ANI (n = 11) and SAL (n = 11) groups showed similar levels of ChR2 labeling. Both groups showed light-induced freezing behavior 1 day post-training (Engram Activation 1), pre-SAL (P < 0.001), pre-ANI (P < 0.02). 2 days post training, (Test 1) the fear memory was reactivated by exposure to Context B, and SAL or ANI injected. 3 days post-training, (Test 2) the ANI group froze significantly less than SAL to Context B (p < 0.01). 4 days post-training, (Engram Activation 2) significant light-induced freezing was observed for the SAL (p < 0.001) and ANI (p < 0.003) groups.

(E) DG Inception (Materials and Methods) following contextual memory amnesia. Context-only engram was labeled for target Context A, followed by injection of SAL (n = 11) or ANI (n = 11). Amnesia demonstrated in ANI group by decreased ChR2+/c-Fos+ co-labeling following Context A re-exposure 1 day post labeling.

Following fear inception, neither SAL nor ANI groups displayed freezing behavior in Context B, while both groups displayed significant freezing in Context A, with no significant difference between groups. No-light inception SAL (n = 7) and ANI (n = 6) controls displayed no freezing to Context A or B. Statistical comparison are performed by using unpaired t tests, *** p < 0.001.

Data presented as mean ± SEM.