A homecage operant paradigm reveals behavioral dynamics of social motivation in mice

We present an open-source, homecage-based social operant paradigm that enables continuous, multi-day measurement of social motivation in mice without experimenter intervention. In this task, a nose-poke response triggers an automated door that provides controlled access to a social partner in an adjacent cage. Using this system, we demonstrate that operant responding is specifically driven by access to a social partner and reveals robust daily rhythms of social motivation across the circadian cycle. We further show that social seeking in this task is sensitive to pharmacological manipulation of dopamine signaling. By combining operant rigor with continuous homecage monitoring, this method increases ecological validity, temporal resolution, and scalability, providing a flexible platform for studying social motivation and its neural regulation in both basic and disease-relevant contexts.