Inactivation of ventral hippocampus interfered with cued-fear acquisition but did not influence later recall or discrimination

• We tested the role of the ventral hippocampus on cued fear learning and discrimination.
• Inactivation of ventral hippocampus impaired cued fear learning.
• Inactivation of ventral hippocampus did not influence fear expression.
• Inactivation of ventral hippocampus did not influence fear discrimination.

The ventral hippocampus (VH) is involved in the both the acquisition and recall of conditioned fear. Here, we tested the role of VH in acquisition and recall of a conditioned fear discrimination. Intra-VH vehicle or muscimol injections were made 1 h prior to a CS+/CS− conditioning or prior to later recall. Vehicle treated rats exhibited discrimination with significantly greater freezing to the CS+ than to the CS− whereas muscimol treated rats did not freeze. Injections made before recall had no effect as both treatment groups displayed equal freezing in response to the CS+, and discrimination. While these results are consistent with several reports, the failure to influence fear discrimination upon recall appears to contrast with the hypothesized role of VH in recall of extinguished conditioned fear cues.