Robust localization and lateralization of human language function: an optimized clinical functional magnetic...

Area of Science:

• Neuroimaging
• Cognitive Neuroscience
• Clinical Neurology

Background:

• Accurate localization of language-critical areas (Broca's and Wernicke's) is essential for neurosurgical planning.
• Individual variability in language area anatomy necessitates personalized functional mapping.
• Existing functional MRI (fMRI) protocols may be time-consuming, posing challenges in clinical settings.

Purpose of the Study:

• To develop and validate an optimized 8-minute clinical fMRI protocol.
• To robustly localize Broca's and Wernicke's areas and determine language hemispheric dominance.
• To provide reference data for BOLD signal characteristics and lateralization index.

Main Methods:

• Utilized block-designed blood oxygenation level dependent (BOLD) fMRI at 1.5 T in 14 right-handed volunteers.
• Employed two language tasks: sentence generation (SG) and word generation (WG) under visual stimulation.
• Assessed BOLD clusters for anatomical localization, calculating signal change (dS%), cluster size, and coordinates.

Main Results:

• Successfully localized Broca's area in the inferior frontal gyrus and Wernicke's area in the superior/middle temporal gyri.
• Reported mean BOLD signal changes for Broca's area (1.53%-2.56%) and Wernicke's area (1.47%-1.80%).
• Calculated a lateralization index (LI) indicating left-hemisphere language dominance, consistent across tasks.

Conclusions:

• The 8-minute fMRI protocol reliably identifies language areas and dominance.
• Demonstrated significant anatomical variability of language areas, underscoring the need for individual mapping.
• The protocol's efficiency and robustness support its clinical utility for pre-surgical language assessment.