A Complete Spatial Map of Mouse Retinal Ganglion Cells Reveals Density and Gene Expression Specializations

Area of Science:

• Neuroscience
• Vision Science
• Computational Biology

Background:

• Retinal ganglion cells (RGCs) are crucial for transmitting visual information.
• Previous studies indicated nonuniform distributions for some RGC subtypes in mice, suggesting functional specialization.
• The complete spatial organization and specialization of all RGC subtypes remain largely uncharacterized.

Purpose of the Study:

• To comprehensively map the spatial distribution of all known mouse RGC subtypes.
• To investigate the functional specialization of RGC subtypes based on their spatial organization.
• To compare the specialization of the mouse visual system with that of primates.

Main Methods:

• En-face cryosectioning for high-resolution retinal imaging.
• Spatial transcriptomics to analyze gene expression patterns across the retina.
• Machine learning algorithms to identify and classify RGC subtypes and their distributions.

Main Results:

• Two-thirds of RGC subtypes exhibited even spatial distribution.
• Specific RGC subtypes showed significant biases towards ventral or dorso-temporal regions, linked to sky vision and the area retinae temporalis (ART).
• Unexpected spatial gene expression variations were observed within subtypes, independent of RGC density.
• Limited correlation was found between the ART and primate macula gene profiles, indicating divergent specialization.

Conclusions:

• Mouse RGCs display diverse spatial distributions, with some subtypes specialized for specific visual fields.
• The ART in mice shows distinct molecular characteristics compared to the primate macula.
• These findings highlight divergent evolutionary paths in central visual system specialization between mice and primates.