Mice lacking the synaptic plasticity-mediating protein calcineurin in their forebrain have behavioural and cognitive abnormalities equivalent to those found in patients with schizophrenia; however, the underlying mechanism is unclear. Hippocampal sharp wave ripple (SWR) events are associated with memory consolidation, and calcineurin-knockout mice were found to exhibit SWRs during post-experience rest periods and lacked the sequential reactivation of hippocampal place cells that normally occurs during SWR events. These data suggest a potential mechanism underlying some of the behavioural alterations seen in schizophrenia.