Abstract

Understanding the dynamic processes of sensory learning and memory is essential for comprehending cognitive function. How neurons undergo synaptic changes at the receptor level in vivo to form a memory engram remains unclear. Here, we employed a genetic approach and identified memory-related (Robust Activity Marking [RAM+]) neuronal ensembles in the barrel cortex following a sensory detection task. Manipulation of RAM+ neurons replicated licking behavior, demonstrating their role in memory encoding. We observed a layer-selective activation pattern during learning with L2/3 excitatory neurons as primary targets. Two-photon in vivo imaging revealed distinct changes in spine surface GluA1 in L2/3 RAM+ and RAM- neurons during learning; both correlate with learning performance. Furthermore, connections between L4 and L2/3 RAM+ neurons were selectively strengthened during learning. Together, these results reveal a learning-induced α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) redistribution toward active neuronal ensembles in a layer-selective manner, which advances our understanding of cellular and synaptic mechanisms underlying sensory memory formation.