Thalamo-cortical coupling during encoding and consolidation is linked to durable memory formation

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Neuroimaging

Background:

• Memory formation relies on stabilizing neural representations (engrams).
• Thalamo-cortical interactions, particularly involving the medioventral thalamus, are crucial for memory stabilization in rodents, but human mechanisms remain unclear.
• Anterior, lateral dorsal, and mediodorsal thalamic nuclei also influence memory.

Purpose of the Study:

• To investigate the role of thalamo-cortical interactions in durable memory formation in humans.
• To test the hypothesis that increased thalamo-cortical connectivity during encoding and consolidation supports durable memory.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was used in 33 human subjects studying picture-location associations.
• Resting-state brain activity was measured pre-study and post-encoding to assess consolidation.
• Memory performance was tested immediately and after a 48-hour delay to differentiate weak from durable memories.

Main Results:

• Durable memory encoding was associated with increased coupling between the medioventral, anterior, lateral dorsal, and mediodorsal thalamus and medial temporal lobe/hippocampus, as well as midline cortical regions.
• Medioventral and lateral dorsal thalamus connectivity with posterior medial and parietal cortex increased post-encoding, correlating with durable memory formation.
• Lateral dorsal thalamus showed consolidation-related coupling with inferior temporal, retrosplenial, and medial prefrontal cortex.

Conclusions:

• Thalamo-cortical cross-talk strengthens memory representations during initial encoding.
• Subsequent cortical coupling of specific thalamic subregions supports memory consolidation.
• These findings elucidate the human neural mechanisms underlying durable memory formation.