EEG connectivity across sleep cycles and age.

Area of Science:

• Neuroscience
• Sleep Science
• Cognitive Neuroscience

Background:

• Sleep is crucial for brain plasticity and cognitive function.
• Cerebral connectivity undergoes significant changes during sleep, especially in young adults.
• Understanding age-related alterations in sleep's neural underpinnings is vital.

Purpose of the Study:

• To investigate age-related differences in electroencephalography (EEG) connectivity during non-rapid eye movement (NREM) and rapid eye movement (REM) sleep.
• To examine how EEG connectivity varies across different sleep stages and cycles in young versus older adults.
• To explore the relationship between sleep EEG connectivity and cognitive performance.

Main Methods:

• Imaginary coherence was used to measure EEG connectivity during NREM and REM sleep.
• Participants included 30 young adults (20-30 years) and 29 older adults (50-70 years).
• Cognitive measures were assessed to explore associations with EEG connectivity.

Main Results:

• Older adults exhibited lower EEG connectivity in N2 sleep but higher connectivity in REM and N3 sleep compared to younger adults.
• Age-related differences in N3 connectivity were prominent in the first sleep cycle.
• EEG connectivity in REM sleep was lower than in N3 sleep, particularly in younger individuals.

Conclusions:

• Age significantly modifies sleep EEG connectivity, with stage- and cycle-specific effects.
• Older brains may have a reduced capacity for neural "disconnection" during N3 and REM sleep compared to younger brains.
• Cerebral functional connectivity during sleep is associated with cognitive functions like processing speed, verbal memory, and intelligence.