Spatial and single-nucleus transcriptomics decoding the molecular landscape and cellular organization of avian optic...

Area of Science:

• Neuroscience
• Molecular Biology
• Comparative Genomics

Background:

• The avian optic tectum (OT) is crucial for visual processing but lacks detailed cellular molecular characterization.
• Understanding its cellular organization is key to deciphering visual perception and associative learning in birds.

Purpose of the Study:

• To comprehensively map the molecular landscape of the avian OT at a single-cell resolution.
• To identify layer-specific gene expression patterns and neuronal subtypes within the OT.
• To explore the functional implications of identified cell populations in avian brain evolution.

Main Methods:

• Spatial transcriptome sequencing was employed to analyze gene expression in tissue context.
• Single-nucleus RNA sequencing (snRNA-seq) provided high-resolution cellular molecular data.
• Comparative analysis was performed on two avian species: *Columba livia* and *Taeniopygia guttata*.

Main Results:

• Precise layer structures of the avian OT were identified with comprehensive layer-specific molecular signatures.
• The stratum griseum periventriculare (SGP) was highlighted for its potential role in advanced functions like fear response and associative learning.
• A novel population of *FOXG1*+ excitatory neurons, similar to mouse neocortical neurons, was discovered, potentially linked to neocortex-related functions and OT expansion.

Conclusions:

• This study provides an unprecedented molecular atlas of the avian OT, detailing its cellular architecture and functional organization.
• The findings illuminate the cellular basis of visual perception and complex cognitive functions in birds.
• The identification of *FOXG1*+ neurons offers insights into avian brain evolution and parallels with mammalian neocortex development.