Fig. 5.

Requirement of neuroligin-1 for storage of associative fear memory. (A) Schematized experimental procedures to test effects of virus infusion on fear conditioning. (B) No statistical difference in freezing levels appeared between control and shNL1 groups during the habituation period (n = 11 rats for control group vs. n = 9 rats for shNL1 group). Before the first auditory cue was given, animals of both groups showed almost no freezing in a recording chamber (context) and they exhibited similar baseline freezing responses to repeated auditory cues during habituation (P > 0.6). (C) There was no statistical difference in freezing level to the cues between the two groups (P > 0.2) during the cue-shock paired fear conditioning. In the contextual fear conditioning test, shNL1 group exhibited significantly less freezing in the conditioned context compared with the control group 24 h after training (***, P < 0.001); control group, 93.5 ± 3.6% vs. shNL1 group, 49.0 ± 7.8%. In the cued fear conditioning test, shNL1 group also exhibited significant reduction of freezing behavior to the shock-associated cues compared with the control group 24 h after training (**, P < 0.01); control group, 88.3 ± 6.1% vs. shNL1 group, 43.9 ± 8.6%.