Sleep Modulates Neural Timescales and Spatiotemporal Integration in the Human Cortex.

Area of Science:

• Neuroscience
• Systems Neuroscience
• Computational Neuroscience

Background:

• Spontaneous neural dynamics exhibit hierarchical organization across the cortex.
• Neural timescales are thought to emerge from microstructural properties, gene expression, and recurrent connections during wakefulness.

Purpose of the Study:

• To investigate the organization and changes in neural timescales from wake to sleep across the cortical hierarchy.
• To characterize two complementary measures of neural timescales: broadband activity and gamma power.

Main Methods:

• Leveraged intracranial electroencephalography (iEEG) in 106 human epilepsy patients.
• Characterized timescale changes from wake to sleep across the cortical hierarchy using broadband and gamma power measures.
• Analyzed spatial correlations as a proxy for spatiotemporal integration.

Main Results:

• Both broadband and gamma neural timescales were globally longer in sleep than in wake.
• Broadband timescales increased along the sensorimotor-association axis, while gamma timescales decreased.
• Slow waves during sleep explained the increase in both broadband and gamma timescales, with broadband timescales positively associated with slow-wave density.

Conclusions:

• Mesoscopic neural populations possess distinct timescales shaped by anatomy and modulated by the sleep-wake cycle.
• Neural timescales exhibit different organizational principles during sleep compared to wakefulness.
• Spatiotemporal integration patterns differ between wake and sleep, with distinct timescale dependencies.