May play an important role in hippocampus-dependent long-lasting memory. Mice are viable and fertile, but show impaired memory retention. Lrrn4-deficient mice are able to maintain memories for one day in hippocampus-dependent learning tasks, but are unable of retaining memories for four days after learning. In contrast, in hippocampus-independent tasks Lrrn4-deficient mice normally retain memories for at least seven days.