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. 2020 Apr 15;40(16):3217–3230. doi: 10.1523/JNEUROSCI.1453-19.2020

Figure 6.

Figure 6.

Silencing VH-PL during testing restores the rapid expression of contextual fear. The ArchT-controls (n = 8) and Trial-silenced (n = 7) groups received two additional CTs. A, During the fourth and fifth retrieval sessions, laser light was delivered to either the Trial-silenced (Test 4) or ArchT-controls (Test 5) to test the state dependency of the contextual fear deficit. B, C, Each point represents the average freezing (± SEM) in a 30 s bin during the first 4 min of retrieval testing for Test 4 (B) and Test 5 (C). The laser was delivered to the designated group during the first minute (green shading). B, Previously impaired Trial-silenced rats exhibit control levels of fear when the VH-PL pathway is silenced again, an effect lasting only as long as the laser was on. When the laser was turned off (Bins 3-8), the retrieval deficits return and then abate, as they did during previous laser-free context testing. C, No light was administered to the Trial group, and the memory deficit is evident. Light delivered to ArchT-control rats did not affect freezing at any time point. These data are summarized in D (left). D, Light was delivered during the first and fifth minute of CT4 and CT5 to assess state-dependent freezing before (min 1) and after (min 5) contextual fear expression was maximal in each group on previous tests. Graphs represent the summary data for all CTs in this study for the first minute (left) and the fifth minute (right). Left, Each point represents the average (± SEM) freezing in the first minute of each CT when the retrieval deficit was maximal on prior tests. The data for CT4 and CT5 here are represented also in the first minute of B and C. BL, Pretraining baseline freezing. BL and CT1-CT3 are presented also in Figure 4. Trial-silenced rats received VH-PL silencing again on Test 4 (green filled circle), and ArchT-control rats received silencing for the first time on Test 5 (green open circle). Right, Each point represents the average (± SEM) freezing in the fifth minute of each CT when the expression of freezing was evident on prior tests. *p < 0.05, between group. #p < 0.05, within group. Holm-Sidak post hoc pairwise tests of a significant three-way interaction (F(5,65) = 3.43, p = 0.0083; ηp² = 0.21).