Fig. 5. EphrinB2 enhances long-term fear memory formation in the basolateral amygdala.

A Mice were injected with ephrinB2-Fc or control Fc into the BLA 30 min before fear conditioning (0.1μg/μl, 0.5 μl in each BLA). Contextual fear conditioning was tested 24 h after fear conditioning and auditory fear memory was tested 48 h after fear conditioning. B Cannula tip placements in the BLA. C There is no difference in freezing during training between the groups (F_(1,17) = 0.132, p = 0.721). D Injection of ephrinB2-Fc into BLA does not affect long-term contextual fear conditioning when compared to Fc-injected animals (t₍₁₇₎ = 1.194, p = 0.249). E Auditory fear memory is significantly enhanced after injection of ephrinB2-Fc (n = 9) into the BLA compared to Fc injection (n = 10) (F_(1,17) = 9.668, p = 0.006). F Fear-conditioned mice injected with ephrinB2 into the BLA (n = 6) had a significantly increased number of c-Fos cells in the BLA 1.5 h after  fear conditioning compared to fear-conditioned mice injected with Fc control (n = 6) (p = 0.026). G Representative labeling of c-Fos in BLA. Arrows show examples of cells labeled with c-Fos in BLA. H EphrinB2 per se did not increase the number of c-Fos in BLA of mice subjected to the conditioning box only (n = 7) when compared to mice subjected to the conditioning box only and injected with Fc (n = 6) (t₍₁₁₎ = 0.561, p = 0.586). Data are presented as mean ± SEM.