Chronobiological Spatial Clusters of Cortical Regions in the Human Brain

Area of Science:

• Neuroscience
• Chronobiology
• Epilepsy Research

Background:

• Spontaneously occurring high-frequency oscillations (HFOs) are electrophysiological markers often studied in epilepsy.
• Understanding the temporal dynamics of cortical activity is crucial for brain function and disease research.

Purpose of the Study:

• To investigate diurnal rhythms of HFOs across different cerebral cortical regions.
• To identify spatial clusters of cortical areas with similar HFO temporal patterns.
• To examine the relationship between these chronobiological clusters and established resting-state networks.

Main Methods:

• Stereotactic electroencephalography (SEEG) data from patients were analyzed, excluding regions associated with epilepsy.
• HFO rates were calculated hourly across 24-hour periods for each SEEG channel.
• Cosinor modeling and spatial clustering were used to identify regions with similar diurnal HFO rhythms, followed by comparison with resting-state networks.

Main Results:

• Five distinct clusters of cortical regions with similar diurnal HFO rhythms were identified.
• These clusters were located in specific areas including left perisylvian, left temporal, right perisylvian/parietal, right frontal, and right insular-opercular cortices.
• Significant overlap was observed between these chronobiological clusters and resting-state networks like the default mode, frontoparietal, visual, and mesial temporal networks.

Conclusions:

• This study presents the first evidence of distinct diurnal rhythms in cortical electrographic activity in humans.
• The identified chronobiological clusters align with functional brain networks, suggesting their significance in cognitive processes.
• These findings have implications for understanding brain function, network dynamics, and potentially epilepsy-related mortality.