A CRITICAL PERIOD FOR THE DEVELOPMENT OF THE COGNITIVE MAP

Postnatal maturation of cortical circuits unfolds within a neural architecture that is largely established through molecular programs initiated in utero. Within these structural constraints, experience-dependent activity refines synaptic connectivity and circuit organization. A growing body of work demonstrates that early-life experience can drive profound and lasting circuit modifications during temporally restricted developmental windows known as critical periods, most clearly characterized in primary sensory cortices. How these experiences shape – and whether such temporally restricted windows of plasticity govern – the development of higher-order cortical computations remain largely unknown. The medial entorhinal cortex (MEC), whose grid-cell population dynamics rely on continuous attractor networks (CAN), offers a tractable system in which to examine how early-life sensorimotor experiences shape circuit function. Given the central role of self-motion signals in MEC development and function, we hypothesized that proprioceptive feedback plays an instructive role in the postnatal development of entorhinal circuitry. By chronically ablating proprioception at defined developmental stages, we assessed how this reafferent signal shapes adult circuit function within the constraints of differentially established neural architectures during development. Our results reveal a critical period in the development of the MEC, during which proprioceptive input is required to guide the maturation of entorhinal computation and its low-dimensional population dynamics.