The Unique Fiber Anatomy of Middle Temporal Gyrus Default Mode Connectivity

Area of Science:

• Neuroscience
• Neuroanatomy
• Cognitive Neuroscience

Background:

• The middle temporal gyrus (MTG) is integral to language functions, including lexical comprehension and semantic cognition.
• Understanding the specific white matter connections of the MTG is essential for preserving these language functions during neurosurgical interventions.

Purpose of the Study:

• To delineate the white matter tracts connected to the MTG.
• To enhance semantic function preservation during neurosurgery by providing detailed anatomical insights.

Main Methods:

• Diffusion imaging and tractography were utilized in 10 healthy adult subjects from the Human Connectome Project.
• White matter tracts connecting the MTG were mapped, and a laterality index was computed.
• Tractography findings were validated through 10 postmortem anatomical dissections.

Main Results:

• Two principal white matter bundles originating from the MTG were identified: the inferior longitudinal fasciculus and the superior longitudinal fasciculus.
• A distinct linear arrangement of U-shaped fibers, potentially involved in visual semantic processing, was observed alongside long association fibers.

Conclusions:

• This study elucidates the fiber-bundle anatomy of the MTG, a key region within the brain's language network.
• A deeper comprehension of the MTG's unique white matter connections can advance our understanding of language processing and the role of networks like the default mode network.