Cortex-wide representational drift of different layers

Representational drift, the gradual evolution of neural population codes over days, has been widely documented at the level of single neurons. However, whether drift is organized across larger cortical populations and spatial scales remains unclear. Here, we examined cortex-wide population dynamics under tightly controlled sensory input and behavior. Using widefield calcium imaging, we longitudinally recorded excitatory activity in Layers 2/3 (L2/3) or Layer 5 (L5) across 25 cortical areas while mice performed a whisker-based texture discrimination task. Sensory-evoked activity was tracked over five consecutive days during stable task performance. Population activity patterns reorganized over days, across the cortex, in both layers. This reorganization followed distinct laminar motifs: notably L5 responses exhibited a widespread, monotonic decrease in activity across most cortical areas, whereas L2/3 responses showed spatially localized and heterogeneous changes that were strongest during the sensory period. These laminar differences extended beyond the stimulus period, with L5 exhibiting more prolonged temporal engagement than L2/3. Together, these findings indicate that representational drift can unfold as a process that is coordinated across cortex with distinct laminar profiles. Thus, drift may reflect a structured feature of cortex-wide circuit dynamics.