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Background: Neuronal lamination is a hallmark of the mammalian central nervous system (CNS) and underlies connectivity and function. Initial formation of this tissue architecture involves the integration of various signaling pathways that regulate the differentiation and migration of neural progenitor cells. Results: Here, we demonstrate that mTORC1 mediates critical roles during neuronal lamination using the mouse retina as a model system. Down‐regulation of mTORC1‐signaling in retinal progenitor cells by conditional deletion of Rptor led to decreases in proliferation and increased apoptosis during embryogenesis. These developmental deficits preceded aberrant lamination in adult animals which was best exemplified by the fusion of the outer and inner nuclear layer and the absence of an outer plexiform layer. Moreover, ganglion cell axons originating from each Rptor‐ablated retina appeared to segregate to an equal degree at the optic chiasm with both contralateral and ipsilateral projections displaying overlapping termination topographies within several retinorecipient nuclei. In combination, these visual pathway defects led to visually mediated behavioral deficits. Conclusions: This study establishes a critical role for mTORC1‐signaling during retinal lamination and demonstrates that this pathway regulates diverse developmental mechanisms involved in driving the stratified arrangement of neurons during CNS development. Key Findings: Reduced mTORC1‐signaling in retinal progenitor cells leads to decreases in proliferation and increases in apoptosis.Proliferation and apoptotic deviations precede aberrant retinal lamination best exemplified by a fusion of the outer and inner nuclear layers and the absence of an outer plexiform layer.Aberrant retinal lamination is correlated with irregular dLGN termination topographies.Irregular dLGN termination topographies are associated with visual behavioural changes. [ABSTRACT FROM AUTHOR]

Coronal section of a mouse embryonic head at E16.5 showing green Isl1/2 positive ganglion and amacrine cells within the neural retina in addition to red Caspase‐3 positive cells within the developing eye lid junction. Leif Carlsson, Christoffer Nord, Iwan Jones, Maria Garcia‐Maestre, Anna‐Carin Hägglund https://doi.org/10.1002/dvdy.707.By Christoffer Nord; Iwan Jones; Maria Garcia‐Maestre; Anna‐Carin Hägglund and Leif CarlssonReported by Author; Author; Author; Author; Author [Extracted from the article]