The human mediodorsal thalamus: Organization, connectivity, and function

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Neuroanatomy

Background:

• The human mediodorsal thalamic nucleus (MD) is vital for higher cognitive functions.
• Its detailed anatomical organization and subregion-specific functions are not fully understood.

Purpose of the Study:

• To delineate the topographic organization of the human MD using high-resolution neuroimaging data.
• To investigate the distinct anatomical and functional connectivity patterns of MD subregions, particularly with the prefrontal cortex.
• To elucidate the functional roles of MD subregions in human cognition.

Main Methods:

• Anatomical connectivity-based parcellation using Human Connectome Project data.
• Identification of four fine-grained subregions: medial (MDm), central (MDc), dorsal (MDd), and lateral (MDl).
• Partial least squares analysis correlating prefrontal-subregion connectivity with behavioral measures in 1012 subjects.

Main Results:

• Four distinct MD subregions were identified, aligning with cytoarchitectonic boundaries.
• Each subregion exhibited unique anatomical and functional connectivity profiles, especially with the prefrontal cortex.
• MDm is linked to emotional cognition; MDl to cognitive flexibility and inhibition; MDc and MDd to fluid intelligence, processing speed, and emotional cognition.

Conclusions:

• This study provides a detailed map of the human MD's anatomical and functional organization.
• Different MD subregions play specific roles in diverse cognitive functions.
• Highlights the critical involvement of prefrontal-thalamic circuits in human cognition.