This editorial argues that there is evidence for memory priming during adequate anaesthesia, and that research in the field of social cognition suggests that such priming may have important behavioural consequences. Comments made in the operating room about a patient's prognosis, appearance or state of consciousness could exacerbate their existing anxieties about the operation, themselves or the anaesthetic and may contribute to postoperative anxiety, depression and insomnia

Andrade, J.

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PubMed

White Rose Research Online

This is a repository copy of Does memory priming during anesthesia matter?.White Rose Research Online URL for this paper:http://eprints.whiterose.ac.uk/928/Article:Andrade, J. (2005) Does memory priming during anesthesia matter? Anesthesiology, 103 (5). pp. 919-920. ISSN 0003-3022 eprints@whiterose.ac.ukhttps://eprints.whiterose.ac.uk/Reuse Unless indicated otherwise, fulltext items are protected by copyright with all rights reserved. The copyright exception in section 29 of the Copyright, Designs and Patents Act 1988 allows the making of a single copy solely for the purpose of non-commercial research or private study within the limits of fair dealing. The publisher or other rights-holder may allow further reproduction and re-use of this version - refer to the White Rose Research Online record for this item. Where records identify the publisher as the copyright holder, users can verify any specific terms of use on the publisher’s website. Takedown If you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing eprints@whiterose.ac.uk including the URL of the record and the reason for the withdrawal request. ! EDITORIAL VIEWSAnesthesiology 2005; 103:1–1 © 2005 American Society of Anesthesiologists, Inc. Lippincott Williams & Wilkins, Inc.Does Memory Priming during Anesthesia Matter?THE article in this issue of ANESTHESIOLOGY by Iselin-Chaves et al.1 consolidates recent evidence that memory“priming” persists during adequate anesthesia. We arenow in a position to move on from wondering whethermemory priming happens during anesthesia to askinghow much happens, under what conditions does it hap-pen, and what is its impact on patients’ well-being.Research in psychology shows that even this very basicform of learning can have profound effects on behavior.Early studies of learning during anesthesia producedequivocal results with interpretation hampered by in-consistent methodology.2 An important recent develop-ment is the combining of careful memory testing withmonitoring of intraoperative awareness or anestheticdepth. Iselin-Chaves et al. presented the repetitions ofeach stimulus word consecutively while recording theBispectral Index (BIS), allowing estimation of the anes-thetic depth at which each word was presented. Theyfound implicit memory for words presented with BISbetween 41 and 60. Implicit memory refers to memoriesthat we are unaware of, that we cannot consciouslyrecall or recognize, but that reveal themselves throughchanges in behavior. Implicit memory is often preservedafter brain damage or experimental manipulations thatabolish conscious recall.The type of learning demonstrated by Iselin-Chaves etal. is actually very limited. If human memory is concep-tualized as a network of nodes representing differentpieces of information, the simplest form of learning istemporary activation of a single node, known as percep-tual priming because it facilitates subsequent percep-tion of stimuli against background noise or, as here, fromfragments such as word stems. Spread of activation torelated nodes (e.g., tractor ¡ farm) is known as concep-tual priming because it facilitates perception of, orresponding with, conceptually related information. Con-ceptual priming is prevented by adequate anesthesia.3In contrast, perceptual priming seems to be preservedduring anesthesia.3 Lubke et al.4 showed enhanced wordstem completion performance for words presented dur-ing trauma surgery with isoflurane, with BIS between 40and 60. The study by Iselin-Chaves et al. extends thesefindings to elective surgery with isoflurane. We found5and then replicated6 word stem completion primingduring elective surgery with relatively deep propofolanesthesia (median BIS ! 42 and 405,6). Perceptual prim-ing thus seems to be a general feature of anesthesia, nota peculiarity of a particular anesthetic technique.The findings are still mixed, however. Kerssens et al.7tested patients undergoing elective surgery and used aword stem completion task but found no evidence forpriming during BIS-guided propofol or isoflurane anes-thesia. They suggested that maintaining a constant anes-thetic depth prevents priming. In the study of Iselin-Chaves et al., moments of light anesthesia just before orafter presentation of a particular word may have facili-tated priming, but this explanation does not apply to ourown demonstration of priming.6 We found priming evenin a retrospectively selected subgroup of patients forwhom BIS happened to remain below 60 throughoutword presentation. The evidence for priming duringanesthesia is not simply an artifact of inadequate depthcontrol.It is generally true, though, that memory activation ismore likely with lighter anesthesia. It is more likely tooccur with opiate-based techniques than with volatileanesthetics that produce deeper hypnosis,8 and it doesnot occur when BIS is less than 40.1,4 The exact relationbetween priming and depth is not clear. Lubke et al.4found a significant although not very strong linear rela-tion between memory and anesthetic depth at whichwords were presented. However, the measure of mem-ory used in this analysis included explicit as well asimplicit components. Using a measure specifically ofimplicit memory, Iselin-Chaves et al. found as muchmemory for words presented during anesthetic depthsof BIS 41–60 as for words presented to volunteers re-ceiving no anesthesia (and no surgery). Their inclusionof a group of awake participants is interesting because itraises the question of whether priming during anesthesiais a mere shadow of priming activity in the consciousbrain or whether perceptual priming is insensitive to allbut the most extreme manipulations of brain function.Their finding suggests that a sudden decrease in percep-tual priming occurs when anesthetic depth decreasesbelow BIS of 40, but until then, it is unaffected by thetransition from consciousness to unconsciousness.Another factor affecting memory priming is the pres-ence of surgical stimulation. The sudden increase inconcentrations of circulating catecholamines caused bysurgery may enhance any residual memory function viathe amygdala.5,9 Fear conditioning occurs in the amyg-dala,10 as does enhancement of memory consolidationduring emotional events or when experimental applica-This Editorial View accompanies the following article: Iselin-Chaves IA, Willems SJ, Jermann FC, Forster A, Adam SR, Vander Linden M: Investigation of implicit memory during isoflu-rane anesthesia for elective surgery using the process dissoci-ation procedure. ANESTHESIOLOGY 2005; 103:000–000.!Accepted for publication July 29, 2005. Supported by grant No. 065503 fromWellcome Trust, London, United Kingdom.Anesthesiology, V 103, No 5, Nov 2005 1balt6/z7i-anesth/z7i-anesth/z7i01105/z7i5357-05a schweigg S!4 9/8/05 9:22 Art: 169510 Input-nlmtions of norepinephrine mimic natural stress.11 Wefound no evidence for priming when words were pre-sented during anesthesia but before surgery, but signifi-cant priming at equivalent anesthetic depth duringsurgery.5 Most stimulus presentation in the study ofIselin-Chaves et al. was completed before surgery began,making their priming effect more impressive than itmight seem at first glance.Therefore, some memory function persists during clin-ically adequate anesthesia. Patients do not learn newinformation or even new associations between alreadyfamiliar information. All that happens is slight activationof existing representations of words in memory detect-able on a carefully designed memory test. Given thatpatients are unlikely in everyday life to be asked tocomplete memory tests, is this any cause for concern?Research in psychology suggests it may be, showingprofound effects on behavior of even this very rudimen-tary memory activity. In what has become a classicexperiment, Bargh et al.12 asked participants to rear-range word lists into sentences. When the lists includedwords relating to the concept of old age (e.g., conserva-tive, wrinkle), participants subsequently walked awayfrom the laboratory more slowly than participants ex-posed to neutral words, even though they had not no-ticed the repeated occurrence of references to old age.Conversely, priming of the concept of professor im-proved performance on a test of general knowledge.13Physiology is not immune to these priming effects: Hullet al.14 found that subliminal exposure to an “angry”prime increased blood pressure relative to exposure to a“relax” prime.You can only prime behaviors that are likely to happenanyway. Surreptitious exposure to words related tospeed led to better performance on a timed test ofintelligence than exposure to neutral words, but onlywhen participants already had the goal of working quick-ly.15 People poured themselves a larger drink, and drankmore of it, after subliminal presentations of smiling facescompared with angry faces, but only if they were alreadythirsty.16 Subliminal priming of the concept “blacks” ledwhite participants to form a more negative impression ofsomeone described verbally, but only if they already hadhigh levels of prejudice.17These laboratory studies show that priming of con-cepts in memory, occurring without participants’ aware-ness, can affect behavior in many ways, making peopleseem slower, thirstier, more prejudiced, or more intelli-gent. Iselin-Chaves et al. have shown that priming canstill happen when patients are anesthetized. Commentsmade in the operating room about a patient’s prognosis,appearance, or state of consciousness could exacerbatetheir existing anxieties about the operation, about them-selves, or about the anesthetic and may contribute topostoperative anxiety, depression, and insomnia even inpatients with no explicit recollection of surgery.Jackie Andrade, Ph.D., Department of Psychology, University ofSheffield, Sheffield, United Kingdom. j.andrade@sheffield.ac.ukReferences1. Iselin-Chaves IA, Willems SJ, Jermann FC, Adam SR, Van der Linden M:Investigation of implicit memory during general anesthesia for elective surgeryusing the process dissociation procedure. ANESTHESIOLOGY 2005; 103:000–0002. Andrade J: Learning during anaesthesia: A review. Br J Psychol 1995;86:479–5063. Deeprose C, Andrade J: Is priming during anesthesia unconscious? Con-scious Cogn 2005; (in press)4. Lubke GH, Kerssens C, Phaf H, Sebel PS: Dependence of explicit andimplicit memory on hypnotic state in trauma patients. ANESTHESIOLOGY 1999;90:670–805. Deeprose C, Andrade J, Varma S, Edwards N: Unconscious learning duringsurgery with propofol anaesthesia. Br J Anaesth 2004; 92:171–76. Deeprose C, Andrade J, Harrison N, Edwards N: Unconscious auditorypriming during surgery with propofol and nitrous oxide anaesthesia: A replica-tion. Br J Anaesth 2005; 94:57–627. Kerssens C, Ouchi T, Sebel P: No evidence of memory function withpropofol or isoflurane with close control of hypnotic state. ANESTHESIOLOGY 2005;102:57–628. Ghoneim MM, Block RI, Dhanaraj VJ, Todd MM, Choi WW, Brown CK:Auditory evoked responses and learning and awareness during general anesthe-sia. Acta Anaesth Scand 2000; 44:133–439. Stapleton C, Andrade J: An investigation of learning during propofol seda-tion and anesthesia using the process dissociation procedure. ANESTHESIOLOGY2000; 93:1418–2510. LeDoux JE: Emotion: Clues from the brain. Annu Rev Psychol 1995;46:209–3511. Cahill L, Prins B, Weber M McGaugh JL: Beta-adrenergic activation andmemory for emotional events. Nature 1994; 371:702–412. Bargh JJ, Chen M, Burrows L: Automaticity of social behaviour: Directeffects of trait constructs and stereotype activation on action. J Pers Soc Psychol1996; 71:230–4413. Dijksterhuis A, van Knippenberg A: The relation between perception andbehavior, or how to win a game of Trivial Pursuit. J Pers Soc Psycho 1998;74:865–7714. Hull JG, Slone LB, Meteyer KB, Matthews AR: The nonconsciousness ofself-consciousness. J Pers Soc Psycho 2002; 83:406–2415. Sheeran P, Webb TL, Gollwitzer PM: The interplay between goal inten-tions and implementation intentions. Pers Soc Psychol B 2005; 31:87–9816. Winkielman P, Berridge KC, Wilbarger JL: Unconscious affective reactionsto masked happy versus angry faces influence consumption behavior and judg-ments of value. Pers Soc Psychol B 2005; 31:121–3517. Lepore L, Brown R: Category and stereotype activation: Is prejudiceinevitable? J Pers Soc Psycho 1997; 72:275–87balt6/z7i-anesth/z7i-anesth/z7i01105/z7i5357-05a schweigg S!4 9/8/05 9:22 Art: 169510 Input-nlm2 EDITORIAL VIEWSAQ: 1Anesthesiology, V 103, No 5, Nov 2005

Does memory priming during anesthesia matter?

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Does memory priming during anesthesia matter?

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