Reduced fear expression after lesions of the ventral hippocampus.
The hippocampus has a critical role in several fundamental memory operations, including the conditioning of fear to contextual information. We show that the hippocampus is necessary also for unconditioned fear, and that the involved circuitry is at the ventral pole of the hippocampus. Rats with selective hippocampal lesions failed to avoid open arms in an elevated plus-maze and had decreased neuroendocrine stress responses during confinement to a brightly lit chamber. These effects were reproduced by lesions of the ventral half of the hippocampus, but not by damage to the dorsal three-quarters of the hippocampus or the amygdala. Ventral lesions failed to impair contextual fear conditioning or spatial navigation, suggesting that the ventral hippocampus may specifically influence some types of defensive fear-related behavior.
Kjelstrup
Kirsten G
KG
Neuroscience Unit, Norwegian University of Science and Technology, MTFS, 7489 Trondheim, Norway.
Tuvnes
Frode A
FA
Steffenach
Hill-Aina
HA
Murison
Robert
R
Moser
Edvard I
EI
Moser
May-Britt
MB
D000679:Amygdala / Q000473:pathology / Q000503:physiopathology; D000818:Animals; D014151:Anti-Anxiety Agents / Q000008:administration & dosage / Q000494:pharmacology; D001931:Brain Mapping / Q000379:methods; D003345:Corticosterone / Q000097:blood; D018690:Excitatory Amino Acid Agonists / Q000008:administration & dosage / Q000494:pharmacology; D005239:Fear / Q000502:physiology*; D006624:Hippocampus / Q000187:drug effects / Q000473:pathology / Q000503:physiopathology*; D007051:Ibotenic Acid / Q000008:administration & dosage / Q000494:pharmacology; D008297:Male; D018782:Maze Learning / Q000502:physiology*; D008874:Midazolam / Q000008:administration & dosage / Q000494:pharmacology; D051381:Rats; D020318:Rats, Long-Evans
D014151:Anti-Anxiety Agents; D018690:Excitatory Amino Acid Agonists; D007051:Ibotenic Acid; D008874:Midazolam; D003345:Corticosterone