A common modular architecture is present across diverse cortical areas during early development. Using two-photon and widefield calcium imaging in ferrets, researchers found that spontaneous activity in sensory areas (auditory, somatosensory, and visual) and association areas (posterior parietal and prefrontal) exhibited a modular structure similar to that in V1. This modular organization was distributed across the cortical surface, forming functional networks with millimeter-scale correlations. Strong correlations among local populations of neurons were observed in all areas, suggesting a common distributed and modular organization across the cortex during early development. This implies that diverse cortical representations develop based on similar design principles. The study shows that spontaneous activity in the developing cortex is modular and exhibits long-range correlations, indicating a common functional organization across different cortical areas. This modular structure is evident in both sensory and association areas, with similar spatial wavelengths and module amplitudes. The results suggest that the early cortex has a common modular organization that is shared across areas, which later diversifies through experience-dependent processes. The modular organization of spontaneous activity was also observed at the cellular level, with nearby neurons showing strong local correlations. This suggests that the modular structure is not just a macroscopic feature but is also present at the cellular level. The findings indicate that the developing cortex has a common modular organization that serves as a foundation for later area-specific influences. The study highlights the importance of spontaneous activity in understanding the functional organization of the developing cortex. The results suggest that the modular structure of spontaneous activity is a common feature across different cortical areas, which may provide a framework for the development of diverse cortical representations. The findings also raise the possibility that the circuit-level mechanisms generating this functional organization may be common across regions, supporting the idea that the early cortex has a common modular organization that is shared across areas.A common modular architecture is present across diverse cortical areas during early development. Using two-photon and widefield calcium imaging in ferrets, researchers found that spontaneous activity in sensory areas (auditory, somatosensory, and visual) and association areas (posterior parietal and prefrontal) exhibited a modular structure similar to that in V1. This modular organization was distributed across the cortical surface, forming functional networks with millimeter-scale correlations. Strong correlations among local populations of neurons were observed in all areas, suggesting a common distributed and modular organization across the cortex during early development. This implies that diverse cortical representations develop based on similar design principles. The study shows that spontaneous activity in the developing cortex is modular and exhibits long-range correlations, indicating a common functional organization across different cortical areas. This modular structure is evident in both sensory and association areas, with similar spatial wavelengths and module amplitudes. The results suggest that the early cortex has a common modular organization that is shared across areas, which later diversifies through experience-dependent processes. The modular organization of spontaneous activity was also observed at the cellular level, with nearby neurons showing strong local correlations. This suggests that the modular structure is not just a macroscopic feature but is also present at the cellular level. The findings indicate that the developing cortex has a common modular organization that serves as a foundation for later area-specific influences. The study highlights the importance of spontaneous activity in understanding the functional organization of the developing cortex. The results suggest that the modular structure of spontaneous activity is a common feature across different cortical areas, which may provide a framework for the development of diverse cortical representations. The findings also raise the possibility that the circuit-level mechanisms generating this functional organization may be common across regions, supporting the idea that the early cortex has a common modular organization that is shared across areas.