The Emergence of the Spatial Structure of Tectal Spontaneous Activity Is Independent of Visual Inputs

Abstract

Summary: The brain is spontaneously active, even in the absence of sensory stimulation. The functionally mature zebrafish optic tectum shows spontaneous activity patterns reflecting a functional connectivity adapted for the circuit’s functional role and predictive of behavior. However, neither the emergence of these patterns during development nor the role of retinal inputs in their maturation has been characterized. Using two-photon calcium imaging, we analyzed spontaneous activity in intact and enucleated zebrafish larvae throughout tectum development. At the onset of retinotectal connections, intact larvae showed major changes in the spatiotemporal structure of spontaneous activity. Although the absence of retinal inputs had a significant impact on the development of the temporal structure, the tectum was still capable of developing a spatial structure associated with the circuit’s functional roles and predictive of behavior. We conclude that neither visual experience nor intrinsic retinal activity is essential for the emergence of a spatially structured functional circuit. : The influence of retinal inputs on the development of the spontaneous neuronal activity of the tectal circuit is unknown. Pietri et al. show that retinal inputs are dispensable for the development of the spatial structure of spontaneous tectal activity, suggesting that the tectal circuit is preconfigured for its functional role. Keywords: optic tectum, retinal input, development of spontaneous activity, zebrafish, neuronal circuit dynamics, behavior, visual system