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

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.

Embryonic cortical layer 5 pyramidal neurons form an active, transient circuit motif perturbed by autism-associated mutations

“…From E16.5 on, the development of layer 5 pyramidal neurons was consistent with previous models of cortical development: the lower layer neurons migrated up to form a middle layer, containing precursors of all three adult layer 5 pyramidal neuron types, that further developed into the adult layer 5. Interestingly, from E17.5 onwards, we detected increased activity within dendrites, compared to the somas, potentially reflecting inputs driven, directly or indirectly, by the incoming axons of thalamic principal neurons (Antón-Bolaños et al, 2019; Guillamón-Vivancos et al, 2022; Moreno-Juan et al, 2017).…”

“…Cajal-Retzius cells, as early as E14.5 (Yuryev et al, 2016(Yuryev et al, , 2018, and pyramidal neurons, from E15.5 onwards, show calcium transients in their somas, in vivo (Antón-Bolaños et al, 2019;Huang et al, 2020). Moreover, at E14.5, thalamic neurons display correlated activity in vitro, and this correlated activity can reach cortex by E16.5, when thalamic axons arrive in the cortex (Guillamón-Vivancos et al, 2022;Moreno-Juan et al, 2017). However, the time when cortical pyramidal neurons first assemble into circuits with other cortical pyramidal neurons, in vivo, and the point at which activity appears and becomes correlated within these circuits, remains unknown.…”

Nature over Nurture: Functional neuronal circuits emerge in the absence of developmental activity

“…Even in the absence of any sensory stimuli, spontaneous activity patterns, such as retinal waves, are thought to provide informative signals for the self-organization of neuronal circuits during development (Bajar et al 2022; Martini et al 2021; Guillamón-Vivancos et al 2022). In the zebrafish visual system, such spontaneous activity in retinal ganglion cells (RGCs) begins at 2.5-3.5 dpf (Zhang et al 2010, 2016), right before RGCs form functional projections to the optic tectum (by 4 dpf) (Burrill and Easter 1994; Stuermer 1988), illustrating a well-characterized synaptic pathway for visually-guided decisions that could be subject to activity-dependent maturation processes.…”

Unusual Mathematical Approaches Untangle Nervous Dynamics

“…Fully different perceptions such as olfactive, auditory, tactile and visive perceptions could be explained by diverse configurations of the braids connecting every external receptor to the corresponding sensitive cortex. In touch with the suggestion that sensitive pathway conformations might affect cue perception, Guillamón-Vivancos et al [ 29 ] suggest that, despite the tactile information simultaneously activating the tactile and visual neural pathways during the embryonic stage, the pathways reorganize after birth to permit the separate processing of visual and tactile information.…”