Fig. 2

CX3CL1^−/− mice demonstrate impaired associative learning and long-term memory that is disparately impacted by mFKN and sFKN. a Mice were subjected to a standard two-shock training protocol for fear conditioning. Shocks were administered at 3 min and 5 min, and freezing behavior was assessed before and after each shock for a duration of 7 min. All groups of mice performed similarly in this training paradigm. Data were analyzed using two-way ANOVA for repeated measures (n = 8, F (18, 288) = 1.486, p = 0.09). b After 2 weeks, mice were placed back into the context in which they initially experienced a foot shock and monitored for freezing behavior over the course of 3 min. CX3CL1^−/− mice that received AAV-GFP showed significantly less freezing behavior than their WT counterparts. Mice that were administered the AAV-mFKN also showed a similar trend in decreased freezing behavior. Mice administered AAV-sFKN showed a trend towards increased freezing behavior that was more similar to WT mice than mice treated with GFP; however, this trend did not reach significance. Data were analyzed by one-way ANOVA (n = 8, F (3, 65) = 4.210; p < 0.010) with Tukey’s test. *p ≤ 0.05. c Mice were allowed 3 min to acclimate in a novel context before presentation of the conditioned stimulus (tone) for three additional minutes. Freezing was monitored for the duration of the test. All mice displayed normal freezing behavior in response to the conditioned stimulus, and no significant differences were observed between groups. Data were analyzed by two-way ANOVA for repeated measures (n = 8, F (3, 44) = 1.132; p = 0.347)