Working memory performance and thalamus microstructure in healthy subjects.

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Neuroimaging

Background:

• Working memory (WM) research primarily focuses on cortical regions like frontal and parietal areas.
• The role of deep gray matter structures in WM and their connection to cortical networks is less understood.
• Individual structural variations in deep gray matter may influence cortical networks crucial for WM.

Purpose of the Study:

• To investigate if structural variations in deep gray matter affect cortical networks involved in working memory.
• To test the hypothesis linking deep gray matter structure to WM performance.

Main Methods:

• High-resolution structural MRI and diffusion tensor imaging (DTI) were used on 181 healthy subjects.
• Microstructural (mean diffusivity, MD) and macrostructural (volume) variations of six deep gray matter structures were analyzed.
• WM performance was assessed using the n-back task and other neuropsychological tests.

Main Results:

• Increased mean diffusivity (MD) in bilateral thalami significantly correlated with reduced WM performance.
• Voxel-by-voxel analysis indicated thalamic nuclei projecting to prefrontal and parietal cortices showed significant WM score-MD anticorrelation.
• Thalamus microstructure, specifically MD, was identified as a significant structural correlate of WM performance.

Conclusions:

• Thalamus microstructure, not its volume, plays a critical role in modulating working memory capacity.
• Altered thalamic microstructural integrity may impair the regulation of cortical connectivity essential for WM tasks.
• These findings highlight the thalamus as a key deep gray matter structure influencing WM through its microstructural properties.