Mapping the corticoreticular pathway from cortex-wide anterograde axonal tracing in the mouse

Area of Science:

• Neuroscience
• Neuroanatomy
• Motor Control

Background:

• The corticoreticular pathway (CRP) is crucial for motor recovery after central nervous system (CNS) damage.
• Understanding the CRP's origins, trajectory, and laterality is vital for rehabilitation strategies.

Purpose of the Study:

• To map the mouse CRP and compare its characteristics with the corticospinal tract (CST).
• To elucidate the origins, trajectory, and laterality of CRP projections in mice.

Main Methods:

• Systematic search of the Allen Mouse Brain Connectivity Atlas for anterograde tracer injection experiments.
• Quantification of CRP and CST projection strength to specific brain regions (reticular formation motor nuclei and pyramids).
• Correlation analysis to determine relative trajectories of CRP and CST.

Main Results:

• Significant CRP projections identified from motor cortices, anterior cingulate, somatosensory cortex, and medial prefrontal cortex.
• CRP showed stronger projections than CST from most cortical regions, with greater bilateral representation.
• Estimated CRP trajectory was anteromedial to CST in the internal capsule and dorsal in the brainstem.

Conclusions:

• The CRP has widespread cortical origins and robust bilateral projections.
• These findings suggest a greater potential for motor compensation and sparing after CNS injury via the CRP.