Abstract

Fornix problem: Why do lesions of the fornix, which connects the hippocampus (HF) to the medial mammillary nucleus (MMN), often cause no deficits in tasks severely affected by lesions of HF or MMN? Solution: The direct HF feedback to antero ventral (AV) thalamus (MMN [Rightarrow A: implies] AV [Leftrightarrow A: l&r dbl arrow] HF), which is blocked by MMN lesions but not fornix lesions, is sufficient for nonscene-relevant consolidation.