Input-dependent segregation of visual and somatosensory circuits in the mouse superior colliculus during development

Thrilled to share our new paper published today in @ScienceMagazine! Huge congrats to @T_Guillamon and all the coauthors for the great work 👏 @GuilleLBendito @Mar_AnibalM @lpuche_1 @JAMoreno_Bravo @NeuroAlc 🧵1/3 https://t.co/5q8vn0JBCl

— Lopez_Bendito Lab (@GLB_Lab) August 18, 2022

2. At birth, superior colliculus circuit reorganization provides sensory-modality specificity
3. Perinatal retinal waves drive the SC circuit reorganization
4. Failure to timely segregate drives long-lasting circuit alterations 3/3

— Lopez_Bendito Lab (@GLB_Lab) August 18, 2022

Allocating sensory responsibilities

During late embryogenesis, the developing mouse brain has inputs from both visual and sensory systems that activate overlapping regions of the cortex. Guillamón-Vivancos et al. now show how spontaneous activity in the perinatal retina tunes the visual cortex to specialize in interpreting retinal activity as vision. Without such spontaneous retinal activity, this part of the brain will take on somatosensory responsibilities instead. This handshake between the sensory system and the cortical recipient is established during a limited time in the perinatal phase of development. —PJH

Abstract

Whereas sensory perception relies on specialized sensory pathways, it is unclear whether these pathways originate as modality-specific circuits. We demonstrated that somatosensory and visual circuits are not by default segregated but require the earliest retinal activity to do so. In the embryo, somatosensory and visual circuits are intermingled in the superior colliculus, leading to cortical multimodal responses to whisker pad stimulation. At birth, these circuits segregate, and responses switch to unimodal. Blocking stage I retinal waves prolongs the multimodal configuration into postnatal life, with the superior colliculus retaining a mixed somato-visual molecular identity and defects arising in the spatial organization of the visual system. Hence, the superior colliculus mediates the timely segregation of sensory modalities in an input-dependent manner, channeling specific sensory cues to their appropriate sensory pathway.