Effects of ibotenic acid lesions of the dorsal hippocampus on contextual fear conditioning in mice: comparison with mammillary body lesions.

The goals of the present study were to determine if ibotenic acid lesions of the dorsal hippocampus (dHPC) or of mammillary body (MB) of the hypothalamus would induce similar contextual conditioning deficit in a fear-conditioning paradigm, previously developed in mice [Eur. J. Neurosci. 12 (2000) 2575]. Results showed that ibotenic acid lesions of the dHPC or of the MB both induced severe deficits on contextual conditioning but spared auditory conditioning, as compared to controls. This study provides direct evidence for an involvement of dHPC neurones in contextual fear conditioning and is first to demonstrate an involvement of the MB in the mediation of contextual fear conditioning.