The study investigates the common modular architecture across diverse cortical areas in early development. Using two-photon and widefield calcium imaging, researchers examined spontaneous activity in ferrets, a species with well-characterized columnar organization and modular structure in the visual cortex. They found that in animals 7 to 14 days before eye-opening and ear canal opening, spontaneous activity in both sensory (auditory and somatosensory cortex) and association areas (posterior parietal and prefrontal cortex) exhibited a highly organized and modular structure similar to that in V1. This modular activity was distributed across the cortical surface, forming functional networks with millimeter-scale correlations. The modular structure was evident at the cellular level, with strong correlations among local populations of neurons in all examined cortical areas. These findings suggest that diverse cortical representations develop from an initially similar functional organization, indicating that a common modular organization serves as a generic cortical substrate for later area-specific specialization. The results highlight the potential role of modular activity in early cortical development and its implications for the emergence of diverse representations in the mature brain.The study investigates the common modular architecture across diverse cortical areas in early development. Using two-photon and widefield calcium imaging, researchers examined spontaneous activity in ferrets, a species with well-characterized columnar organization and modular structure in the visual cortex. They found that in animals 7 to 14 days before eye-opening and ear canal opening, spontaneous activity in both sensory (auditory and somatosensory cortex) and association areas (posterior parietal and prefrontal cortex) exhibited a highly organized and modular structure similar to that in V1. This modular activity was distributed across the cortical surface, forming functional networks with millimeter-scale correlations. The modular structure was evident at the cellular level, with strong correlations among local populations of neurons in all examined cortical areas. These findings suggest that diverse cortical representations develop from an initially similar functional organization, indicating that a common modular organization serves as a generic cortical substrate for later area-specific specialization. The results highlight the potential role of modular activity in early cortical development and its implications for the emergence of diverse representations in the mature brain.