Massive Multiplexing of Spatially Resolved Single Neuron Projections with Axonal BARseq

Area of Science:

• Neuroscience
• Molecular Biology
• Genomics

Background:

• Cortical neurons exhibit heterogeneity in axonal projections to various brain regions.
• Understanding these projections requires single-neuron resolution, which current high-throughput methods struggle to provide at scale.
• Existing techniques often necessitate combining data from multiple specimens due to limited neuron capacity per brain.

Approach:

• Introduced axonal BARseq, a high-throughput method utilizing in situ RNA sequencing of nucleic acid barcodes.
• Enables analysis of densely labeled neurons, overcoming limitations of previous reconstruction techniques.
• Successfully mapped long-range projections of over 8000 primary auditory cortex neurons from a single mouse brain.

Key Points:

• Identified distinct cell types based on axonal projection targets and trajectories.
• Leveraged large sample size to systematically quantify intratelencephalic (IT) neuron projections.
• Revealed area-dependent, layer-specific projection patterns of individual IT neurons.

Conclusions:

• Axonal BARseq offers a powerful high-throughput technique for studying neuronal projection heterogeneity.
• Facilitates detailed analysis of single neuronal connections within individual brains.
• Advances the understanding of cortical circuit organization and neuronal diversity.