Distinct EEG Features and Sleep/Wake Behaviour Predict Anxiety Phenotypes in Mice

Area of Science:

• Neuroscience
• Sleep Science
• Animal Behavior

Background:

• Preoperative anxiety is a common issue impacting surgical outcomes.
• Current anxiety assessments are subjective, highlighting the need for objective biomarkers.
• Understanding the neurobiological underpinnings of anxiety is crucial for developing better diagnostic tools.

Purpose of the Study:

• To investigate if baseline electroencephalography (EEG) and sleep-wake profiles predict anxiety levels in a mouse model.
• To identify objective EEG and sleep biomarkers associated with high-anxiety phenotypes.
• To explore the relationship between sleep architecture and anxiety-like behaviors.

Main Methods:

• Fifty male C57BL/6N mice underwent EEG/EMG implantation and baseline recordings.
• Mice were subjected to a cued fear-conditioning protocol.
• K-medoids clustering based on behavioral indices classified mice into high-anxiety (HA) and low-anxiety (LA) groups.

Main Results:

• High-anxiety mice exhibited altered baseline sleep architecture, including reduced REM sleep (REMS) and increased NREMS during the dark period.
• Spectral analysis revealed lower delta power and heightened eta/beta activity during REMS in HA mice.
• HA mice displayed longer and higher-amplitude sleep spindles, indicating disrupted sleep microstructure.

Conclusions:

• Specific baseline EEG and sleep-wake parameters can predict distinct anxiety phenotypes in mice.
• These findings suggest that sleep microstructure alterations are linked to enhanced anxiety-like responses.
• This research may pave the way for objective biomarkers to identify individuals susceptible to anxiety, including preoperative anxiety.