Separation of pups from their mother mice enhances odor associative learning at the late lactation stage

During lactation, mammalian pups rely on the dam for survival and associative learning related to maternal stimuli. This study investigates how maternal preference shifts during the late lactation period in mouse pups. Pups conditioned with odorized dams during this period exhibited distinct preferences: those exposed to 4-methylthiazole (4MT) preferred it, while controls avoided it, and eugenol (EG)-conditioned pups showed no response. Interestingly, dams painted with 4MT displayed reduced maternal care compared to EG- or oil-painted dams. To separate maternal presence from odor experience, pups were exposed to 4MT or EG without the dam. Odor-preference learning occurred only when pups remained with their siblings but failed when separated from both the dam and all of their siblings. These findings suggest that dam separation in the presence of siblings facilitates odor-preference learning, indicating a developmental shift towards reduced dam reliance and preparation for independence.