Department of Psychology and Speech-Language Pathology, and Turku Brain and Mind Center, University of Turku, Turku, Finland; Department of Perioperative Services, Intensive Care and Pain Medicine, Turku University Hospital, Turku, Finland.
Department of Perioperative Services, Intensive Care and Pain Medicine, Turku University Hospital, Turku, Finland; Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland.
Br J Anaesth. 2018 Jul;121(1):270-280. doi: 10.1016/j.bja.2018.04.032. Epub 2018 May 23.
Studying the effects of anaesthetic drugs on the processing of semantic stimuli could yield insights into how brain functions change in the transition from wakefulness to unresponsiveness. Here, we explored the N400 event-related potential during dexmedetomidine- and propofol-induced unresponsiveness.
Forty-seven healthy subjects were randomised to receive either dexmedetomidine (n=23) or propofol (n=24) in this open-label parallel-group study. Loss of responsiveness was achieved by stepwise increments of pseudo-steady-state plasma concentrations, and presumed loss of consciousness was induced using 1.5 times the concentration required for loss of responsiveness. Pre-recorded spoken sentences ending either with an expected (congruous) or an unexpected (incongruous) word were presented during unresponsiveness. The resulting electroencephalogram data were analysed for the presence of the N400 component, and for the N400 effect defined as the difference between the N400 components elicited by congruous and incongruous stimuli, in the time window 300-600 ms post-stimulus. Recognition of the presented stimuli was tested after recovery of responsiveness.
The N400 effect was not observed during dexmedetomidine- or propofol-induced unresponsiveness. The N400 component, however, persisted during dexmedetomidine administration. The N400 component elicited by congruous stimuli during unresponsiveness in the dexmedetomidine group resembled the large component evoked by incongruous stimuli at the awake baseline. After recovery, no recognition of the stimuli heard during unresponsiveness occurred.
Dexmedetomidine and propofol disrupt the discrimination of congruous and incongruous spoken sentences, and recognition memory at loss of responsiveness. However, the processing of words is partially preserved during dexmedetomidine-induced unresponsiveness.
NCT01889004.
研究麻醉药物对语义刺激处理的影响，可以深入了解大脑功能在从清醒到无反应状态的转变过程中是如何变化的。在这里，我们探讨了右美托咪定和丙泊酚诱导无反应状态时的 N400 事件相关电位。
47 名健康受试者被随机分为右美托咪定组（n=23）或丙泊酚组（n=24），这是一项开放标签的平行组研究。通过逐步增加假性稳态血浆浓度来实现无反应性，并用达到无反应所需浓度的 1.5 倍来诱导假定的意识丧失。在无反应期间，呈现用预期（一致）或意外（不一致）词结尾的预先录制的口语句子。对脑电图数据进行分析，以确定 N400 成分的存在，以及在刺激后 300-600ms 的时间窗口内，由一致和不一致刺激引起的 N400 成分之间的差异（定义为 N400 效应）。在恢复反应性后，对呈现的刺激进行识别测试。
在右美托咪定或丙泊酚诱导的无反应期间，未观察到 N400 效应。然而，在右美托咪定给药期间，N400 成分仍然存在。在右美托咪定组无反应期间，一致刺激引起的 N400 成分类似于清醒基线时不一致刺激引起的大成分。恢复后，对无反应期间听到的刺激没有识别。
右美托咪定和丙泊酚破坏了对一致和不一致口语句子的区分能力，以及无反应时的识别记忆。然而，在右美托咪定诱导的无反应期间，单词的处理部分保留。
NCT01889004。
