The third branch of the superior longitudinal system

Area of Science:

• Neuroscience
• Neuroanatomy
• Brain Connectivity

Background:

• The superior longitudinal system is a major associative fiber pathway in the brain.
• Understanding its distinct components, like the third branch, is crucial for mapping brain function.

Purpose of the Study:

• To review current knowledge on the third branch of the superior longitudinal system (SLS).
• To delineate its anatomy, function in healthy individuals, and roles identified through lesion studies and intraoperative stimulation.

Main Methods:

• Review of existing literature on the third branch of the SLS.
• Analysis of lesion-symptom mapping studies.
• Examination of intraoperative electrostimulation findings.

Main Results:

• The third branch of the SLS is anatomically and functionally distinct.
• It differs from the arcuate fasciculus, despite overlapping trajectories.
• Evidence suggests lateralized functional roles for the right and left third branches of the SLS.

Conclusions:

• The third branch of the SLS is a well-defined neural pathway.
• It plays unique roles separate from the arcuate fasciculus.
• A new anatomo-functional model with three subcomponents is proposed for the third branch of the SLS.