Figure 4.

Effect of medial prefrontal cortex (mPFC) α-1 adrenergic blockade on extinction memory in sham and neonatal ventral hippocampus (nVH)-lesioned animals. (a) Extinction learning curve of rats infused with either artificial cerebrospinal fluid (ACSF) or benoxathian (Benox or Ben) bilaterally into infralimbic PFC, 30 min before the session (arrow sign). (b) Bar diagram of mean (±SEM) freezing response at the last block of two trials in the four groups of animals. Sham animals with mPFC benoxathian infusion, compared with ACSF, show higher freezing indicating resistance to extinction learning. However, the α-1 adrenergic receptor (α-1AR) antagonist has no significant effect in nVH-lesioned animals, that is, do not exacerbate extinction deficit of lesioned animals (*p=0.002 and ^#p=0.004 compared with sham-ACSF group. (c) Freezing responses of the animals during the extinction recall. (d) Mean±SEM of freezing response at the last block of two-tone trials during recall (^#p=0.0003 compared with sham-ACSF).