Three-dimensional X-ray visualization of axonal tracts in mouse brain hemisphere

Area of Science:

• Neuroscience
• Biophysics
• Medical Imaging

Background:

• Neurons transmit electrical signals via axons, crucial for brain function.
• Visualizing intricate axonal networks is essential for understanding neural circuitry.
• Existing methods face limitations in resolving fine axonal structures in 3D.

Purpose of the Study:

• To visualize and reconstruct 3D axonal networks in the murine brain.
• To investigate the microstructural basis of contrast in X-ray imaging of brain tissue.
• To establish a method for delineating functional relationships within brain networks.

Main Methods:

• Freeze-drying of murine brain samples to enhance intrinsic contrast.
• X-ray tomographic microscopy (micro-CT) for 3D visualization.
• Absorption contrast and phase retrieval methods for imaging at up to 2.7 μm resolution.

Main Results:

• Successful visualization of 3D brain structures, including the striatum, corpus callosum, and anterior commissure.
• Identification of axonal tracts originating from the cerebral cortex and terminating in the basal ganglia.
• Correlation of X-ray attenuation coefficients with myelin sheath composition (water and phospholipid content).

Conclusions:

• X-ray microtomography provides high-resolution 3D imaging of brain axonal networks.
• Contrast in micro-CT is primarily due to differences in myelin sheath composition.
• This technique enables reconstruction and analysis of neural pathways for functional studies.