Discrete and sequential critical periods organise the development of task-specific sensorimotor circuits in mice

Somatosensory circuits in early life must maintain stable, task-selective pathways while behavioural repertoires undergo rapid change. How such circuits construct these behaviours under evolving functional demands has remained unclear. Here we show that sensorimotor behaviours are shaped through sequential, experience-dependent critical periods rather than a single global window of plasticity. Using transient perturbations of somatosensory input across postnatal development in mice, we identify three discrete life stages that exert lasting effects on adult behaviour. Perturbation during postnatal days 8-12 selectively increases adult sensitivity to dynamic touch. The same manipulation during days 13-17 produces persistent deficits in motor coordination. Perturbation during days 18-22 instead results in lifelong impairments in skilled locomotion. These findings reveal that somatosensory circuits undergo multiple phases of refinement, each aligned with the changing functional needs of the developing organism. This framework of sequential, task-specific critical periods offers a new model for building lifelong sensorimotor function. Significance StatementDeveloping sensory systems must construct precise neural circuits to support dynamic behaviours that change with postnatal experience. We show that somatosensory circuits achieve this through sequential, task-specific critical periods, rather than a single fixed window of plasticity. This dynamic framework demonstrates how experience can guide the stepwise construction of sensorimotor behaviours, offering a new perspective on critical periods across complex, multimodal systems.