Remote spatial memory deficits in mouse models of neuropsychiatric disorders with immature dentate gyrus phenotype

These results indicated that mouse models of neuropsychiatric and neurodegenerative disorders exhibiting the iDG phenotype demonstrate a common behavioral characteristic of remote spatial memory deficits, suggesting the potential involvement of the pseudo-immature state of DG granule cells in remote memory dysfunction. Significance Statement A pseudo-immature state of granule cells in the hippocampal dentate gyrus (DG), called immature DG (iDG), has been observed in several mutant strains of mice considered as animal models of neuropsychiatric and neurodegenerative disorders. Thus, the iDG phenotype is proposed as one of the characteristic features of some types of the disorders. However, the impacts of iDG phenotype on hippocampal functions remains unclear. This study demonstrated that two of the five genetically modified mouse strains with iDG phenotype exhibited deficits in both recent and remote memory, with the impairments being more pronounced at the remote delay. The other three strains showed selective deficits in remote memory. These observations suggest that the pseudo-immature state of DG is associated with remote memory dysfunction, although further studies are needed to determine the causality and elucidate the underlying mechanisms.