Continuous subcellular resolution three-dimensional imaging on intact macaque brain.

Area of Science:

• Neuroscience
• Brain Mapping
• Connectomics

Background:

• Mapping complex brain circuits requires charting long-distance pathways with high local accuracy.
• Individual-axon resolution mapping in large primate brains remains a significant challenge.

Purpose of the Study:

• To develop an efficient pipeline for high-resolution, 3D whole-brain mapping in macaques.
• To reconstruct individual neuronal projections across the entire brain hemisphere with subcellular detail.

Main Methods:

• A novel poly-N-acryloyl glycinamide (PNAGA)-based embedding for structure and fluorescence preservation.
• High-resolution, rapid whole-brain optical imaging and advanced image post-processing.
• Viral labeling for tracing individual long-distance projection axons from the frontal cortex.

Main Results:

• Acquired whole macaque brain cytoarchitectonic information at 0.32 x 0.32 x 10 μm voxel size.
• Reconstructed individual cortical axons from the prefrontal cortex across the entire hemisphere at 0.65 x 0.65 x 3 μm voxel size.
• Demonstrated that prefrontal cortical axons simultaneously target multiple distant brain regions, including visual cortex, striatum, thalamus, and midbrain.

Conclusions:

• The developed pipeline enables efficient cellular and circuitry investigation of the whole macaque brain at individual-axon resolution.
• This technology provides a powerful tool for understanding brain function and neurological disorders.
• The findings offer unprecedented insights into the long-distance connectivity of the primate brain.