Dreams recall and auditory evoked potentials during propofol anaesthesia

It is unclear whether shorter waves latencies of middle-latency-auditory-evoked-potentials (MLAEPs) may be associated to cognitive function other than non-declarative memory. We investigated presence of declarative, non-declarative and dreaming memory in propofol-anaesthetized patients and any relationship to intraoperatively registered MLAEPs. An audiotape containing one of two stories was presented to patients during anaesthesia. Patients were interviewed on dream recall immediately upon emergence from anaesthesia. Declarative and non-declarative memory for intraoperative listening were assessed 24 hours after awakening without pointing out positive findings. Six patients who reported dream recall showed an intraoperative Pa latency less than that of patients who were unable to remember any dreams (p<0.001). A high responsiveness degree of primary cortex was associated to dream recall formation during anaesthesia.