Retinal waves reveal axial biases in modular patterns of cortical activity that predict future orientation preferences.

Spontaneous activity before sensory onset is thought to guide the formation of functional neural circuits. In visual cortex, spontaneous activity prior to experience exhibits modular patterns that resemble future visually evoked orientation selective responses. However, the factors at this early stage that build the initial network interactions that support the orientation tuning of modular responses at eye opening remain unknown. Here we provide the first evidence that retinal waves could play an important role by shaping the modular biases in patterns of intracortical connectivity and lay the foundation for orientation selective responses. We demonstrate that slow propagating waves in developing cortex that are dependent on retinal activity recruit specific modular patterns during their movement across the cortical surface, resulting in strikingly elongated patterns of modular coactivity that predict visually-evoked orientation responses at eye opening. Thus axial biases in spontaneous patterns of co-activity are present before the onset of visual experience and could serve as the seed for the developmental emergence of modular orientation representations.