Individualized Functional and Structural Language Lateralities in Temporal Lobe Epilepsy and Their Impact on Memory

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Neuroimaging

Background:

• Understanding functional brain asymmetries, especially language lateralization, and their link to structural asymmetries is limited.
• The influence of functional language asymmetries on memory organization requires further investigation.

Purpose of the Study:

• To assess the concordance between hemispheric language laterality and gray matter structural asymmetries.
• To determine if functional language asymmetries influence the hemispheric organization of memory.

Main Methods:

• Acquired structural and functional MRI data from 261 participants (unilateral temporal lobe epilepsy patients and healthy controls).
• Calculated standard and targeted language laterality indices (LIs) for functional and structural data.
• Employed discriminant and partial least squares analyses to evaluate group differences and cognitive relationships.

Main Results:

• Significant shifts in language laterality were found in left temporal lobe epilepsy (LTLE) patients compared to healthy participants.
• Strong correlations existed between functional LIs and structural LIs (ST-LIs).
• Targeted LIs and ST-LIs effectively differentiated TLE patients from controls, with ST-LIs being the strongest predictor.
• Verbal and visual memory showed a direct dependence on targeted LIs, particularly in healthy participants and LTLE patients.

Conclusions:

• Individualized, region-specific measures are crucial for understanding language laterality and its structural basis.
• Functional language asymmetries significantly impact memory organization, with varying effects across patient groups and healthy individuals.
• The findings highlight the intricate relationship between brain structure, language function, and cognitive processes like memory.