Functional Contributions of the Arcuate Fasciculus to Language Processing

Area of Science:

• Neuroscience
• Neurolinguistics
• Neuroanatomy

Background:

• The arcuate fasciculus (AF) is implicated in various language functions.
• Its precise role and contribution beyond cortical language areas require further investigation.

Purpose of the Study:

• To comprehensively evaluate the specific functional role of the AF in chronic aphasia post-left hemisphere stroke.
• To delineate the contribution of AF segments to language processing, independent of cortical areas.

Main Methods:

• Tractography using constrained spherical deconvolution to assess AF macro- and microstructural integrity.
• Manual reconstruction of AF segments using established models (Catani et al., 2005; Glasser & Rilling, 2008).
• Multiple regression analyses to determine AF segment contributions to language indices, controlling for cortical areas and lesion volume.

Main Results:

• Left hemisphere AF segments, particularly the posterior segment, significantly correlated with language indices (comprehension, naming, fluency).
• The long AF segment contributed to naming; the anterior segment to fluency and naming; the posterior segment to comprehension.
• No significant role for the right hemisphere AF in language processing was identified.

Conclusions:

• The left AF plays a significant role in language processing, especially comprehension and naming, beyond cortical contributions.
• The posterior segment of the left AF is critical for supporting residual language abilities after stroke.