Intracranial electroencephalography features of young and old mice under midazolam administration

Understanding the electroencephalography features of young and old patients treated with anesthetic drugs is important to allow accurate drug use in elderly patients. This study aimed to monitor the intracranial electroencephalography (in the cortex and hippocampus) in free-moving young and old mice under midazolam administration. Behavioral assessment revealed that compared with young mice, old mice had a longer immobility time with a similar midazolam dose. In both young and old mice, midazolam significantly suppressed the total, δ (0.5–4 Hz), θ (4–8 Hz), and α (8–12 Hz) power, and thus induced an increase in the relative β (12–30 Hz) and γ (30–140 Hz) power. Age had a main effect on the γ frequency; specifically, under normal conditions, old mice had a lower γ power than young mice. After midazolam administration, the relative power of high γ frequency (50–140 Hz) remained lower in old mice than in young mice. Our findings suggest that a lower γ power is indicative of an aging brain.