A critique of the vasopressin-memory hypothesis.

During the past 20 years, evidence has accumulated to suggest that the neuropeptide vasopressin (VP) enhances memory by acting on central mechanisms, and that oxytocin (OT) has amnestic effects. In this review, the evidence for the memory hypothesis with respect to VP is considered and alternative interpretations evaluated. A critical approach has been adopted; negative findings, design considerations and problems with the various hypotheses are given prominence. It is concluded that the memory hypothesis fails to provide an adequate account, and some alternative theories and suggestions are discussed. It is speculated that the peptide may affect behaviour by two distinct mechanisms: peripheral action may involve reinforcement mechanisms, but its central role may be to modulate arousal level, especially in stressful situations.