Posterior parietal cortex guides sensorimotor associative learning by linking sensation to distal action

Sensorimotor associative learning is challenged when sensory cues and motor responses are separated by a delay, limiting the coactivity required for Hebbian plasticity. Here we identify the rostro-lateral posterior parietal cortex (PPC-rl) as a cortical hub that bridges tactile stimuli and delayed licking during learning. Using cortex-wide calcium imaging with single-cell resolution to track ~16,000 neurons simultaneously across sensory, motor, and association cortices, we find that PPC-rl exhibits sustained delay-epoch activity early in learning that diminishes with expertise. Optogenetic silencing slows learning without impairing expert motor execution. Learning strengthens intra- and inter-areal sensorimotor coupling, and PPC-rl mediates this process by amplifying a low-dimensional communication subspace that aligns sensorimotor co-fluctuations. A biologically plausible network model shows that PPC-rl persistence, subspace alignment, and reward-gated Hebbian plasticity synergize to support delayed association. These findings uncover a PPC-rl based cortical mechanism that maintains temporal continuity to link sensation with distal action during learning.