New insights on the modeling of the molecular mechanisms underlying neural maps alignment in the midbrain

Abstract

We previously identified and modeled a principle of visual map alignment in the midbrain involving the mapping of the retinal projections and concurrent transposition of retinal guidance cues into the superior colliculus providing positional information for the organization of cortical V1 projections onto the retinal map (Savier et al., 2017). This principle relies on mechanisms involving Epha/Efna signaling, correlated neuronal activity and axon competition. Here, using the 3-step map alignment computational model, we predict and validate in vivo the visual mapping defects in a well-characterized mouse model. Our results challenge previous hypotheses and provide an alternative, although complementary, explanation for the phenotype observed. In addition, we propose a new quantification method to assess the degree of alignment and organization between maps, allowing inter-model comparisons. This work generalizes the validity and robustness of the 3-step map alignment algorithm as a predictive tool and confirms the basic mechanisms of visual map organization.

Segregation of Multimodal Inputs Into Discrete Midbrain Compartments During an Early Critical Period

“…Further investigations that replicate the present tracing experiments and quantify the degree of projection overlap in mice lacking necessary Eph-ephrin cues, structured activity, or both, are needed to determine how these distinct afferent sets achieve proper alignment. Such data will be instrumental in developing future computational models that make LCIC mapping predictions based on various experimental conditions, similar to those already being successfully employed in other analogous systems (Reber et al, 2004 ; Yates et al, 2004 ; Tsigankov and Koulakov, 2006 ; Owens et al, 2015 ; Savier et al, 2017 ; Savier et al, 2020 ).…”