Massive multiplexing of spatially resolved single neuron projections with axonal BARseq

Area of Science:

• Neuroscience
• Molecular Biology
• Genomics

Background:

• Cortical neurons exhibit diverse axonal projections, necessitating single-neuron resolution for understanding brain connectivity.
• Current high-throughput reconstruction methods are limited in scale, often requiring pooled data from multiple specimens.

Purpose of the Study:

• To introduce axonal BARseq, a novel high-throughput method for analyzing single neuronal projections.
• To map long-range projections of a large number of neurons from the primary auditory cortex within an individual brain.

Main Methods:

• Axonal BARseq utilizes in situ RNA sequencing to read nucleic acid barcodes from individual neurons.
• This technique allows for the analysis of densely labeled neuronal populations.
• Mapping of >8000 primary auditory cortex neurons from a single mouse.

Main Results:

• Identification of major cell types based on projection targets and axonal trajectories.
• Systematic quantification of intratelencephalic (IT) neuron projections.
• Demonstration that individual IT neurons project to different layers in an area-dependent manner.

Conclusions:

• Axonal BARseq is a powerful tool for high-throughput analysis of single neuronal projections.
• The study reveals significant heterogeneity in neuronal projection patterns within individual brains.
• This technique facilitates a deeper understanding of brain circuitry and neuronal diversity.