Oscillatory and aperiodic neuronal activity in working memory following anesthesia

Abstract

ObjectiveAnesthesia and surgery are associated with cognitive impairment, particularly memory deficits. So far, electroencephalography markers of perioperative memory function remain scarce. MethodsWe included male patients >60 years scheduled for prostatectomy under general anesthesia. We obtained neuropsychological assessments and a visual match-to-sample working memory task with simultaneous 62-channel scalp electroencephalography 1 day before and 2 to 3 days after surgery. ResultsTwenty-six patients completed both pre- and postoperative sessions. Compared with preoperative performance, verbal learning deteriorated after anesthesia (California Verbal Learning Test total recall; t25 = −3.25, p = 0.015, d = −0.902), while visual working memory performance showed a dissociation between match and mismatch accuracy (match*session F1,25 = 3.866, p = 0.060). Better verbal learning was associated with an increase of aperiodic brain activity (total recall r = 0.66, p = 0.029, learning slope r = 0.66, p = 0.015), whereas visual working memory accuracy was tracked by oscillatory theta/alpha (7 – 9 Hz), low beta (14 – 18 Hz) and high beta/gamma (34 – 38 Hz) activity (matches: p < 0.001, mismatches: p = 0.022). ConclusionsOscillatory and aperiodic brain activity in scalp electroencephalography track distinct features of perioperative memory function. SignificanceAperiodic activity provides a potential electroencephalographic biomarker to identify patients at risk for postoperative cognitive impairments.