Substantia nigra iron affects functional connectivity networks modifying working memory performance in younger adults

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Neuroimaging

Background:

• Brain iron levels are known to influence cognitive functions, including working memory (WM).
• The specific relationship between iron concentration in deep grey matter nuclei and the functional connectivity of brain networks supporting WM remains unclear.

Purpose of the Study:

• To investigate if deep grey matter nuclei iron concentration affects resting-state functional connectivity (rsFC) within brain networks.
• To determine how these changes in rsFC, influenced by iron, relate to working memory performance.

Main Methods:

• Utilized N-back tasks to assess working memory in 100 healthy young adults.
• Employed resting-state functional magnetic resonance imaging (fMRI) for brain network analysis.
• Conducted quantitative susceptibility mapping (QSM) to measure deep grey matter nuclei iron concentration.

Main Results:

• Increased iron concentration in the substantia nigra (SN) correlated with reduced rsFC between the SN and temporal/frontal lobe regions.
• Higher SN iron was associated with enhanced working memory performance, even after controlling for demographic factors.
• Mediation analysis suggested that functional connectivity plays a role in linking SN iron levels to WM performance.

Conclusions:

• Elevated substantia nigra iron concentration may alter communication pathways between the SN and temporal/frontal lobes.
• High SN iron is associated with improved working memory performance in younger adults, potentially mediated by changes in functional connectivity.