Cross-regional coordination of activity in the human brain during autobiographical self-referential processing

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Systems Neuroscience

Background:

• Neural coordination across brain regions is crucial for cognitive functions like memory retrieval.
• Understanding the precise temporal dynamics and causal interactions in memory networks remains a challenge.

Purpose of the Study:

• To investigate the millisecond-scale neural coordination and causal interactions among the hippocampus (HPC), posteromedial cortex (PMC), ventromedial/orbital prefrontal cortex (OFC), and anterior nuclei of the thalamus (ANT) during autobiographical memory retrieval.

Main Methods:

• Intracranial electrophysiological recordings from 31 patients during memory retrieval tasks.
• Analysis of low-frequency (LF) and high-frequency (HF) neural activity and cross-regional phase coherence.
• Probing causal interactions using targeted electrical stimulation.

Main Results:

• Memory cues triggered increased LF activity, followed by LF phase coherence across regions, preceding HF neuronal activity.
• HF activity power depended on memory content, with a specific temporal sequence (ANT→HPC/PMC→OFC).
• Hippocampal stimulation most strongly increased LF coherence; stimulation of any region most strongly affected coherence with ANT.

Conclusions:

• The anterior nuclei of the thalamus (ANT) appear to gate, and the hippocampus (HPC) to synchronize, activity in cortical midline structures during self-relevant memory retrieval.
• Findings provide high temporal resolution insights into dynamic signaling and causal connections within memory networks.