title: Can the neural basis of repression be studied in the MRI scanner? New insights from two free association paradigms.
abstract: BACKGROUND
  The psychodynamic theory of repression suggests that experiences which are related to internal conflicts become unconscious. Previous attempts to investigate repression experimentally were based on voluntary, intentional suppression of stimulus material. Unconscious repression of conflict-related material is arguably due to different processes, but has never been studied with neuroimaging methods.
  
  
  METHODS
  We used functional magnetic resonance imaging (fMRI) in addition with skin conductance recordings during two free association paradigms to identify the neural mechanisms underlying forgetting of freely associated words according to repression theory.
  
  
  RESULTS
  In the first experiment, free association to subsequently forgotten words was accompanied by increases in skin conductance responses (SCRs) and reaction times (RTs), indicating autonomic arousal, and by activation of the anterior cingulate cortex. These findings are consistent with the hypothesis that these associations were repressed because they elicited internal conflicts. To test this idea more directly, we conducted a second experiment in which participants freely associated to conflict-related sentences. Indeed, these associations were more likely to be forgotten than associations to not conflict-related sentences and were accompanied by increases in SCRs and RTs. Furthermore, we observed enhanced activation of the anterior cingulate cortex and deactivation of hippocampus and parahippocampal cortex during association to conflict-related sentences.
  
  
  CONCLUSIONS
  These two experiments demonstrate that high autonomic arousal during free association predicts subsequent memory failure, accompanied by increased activation of conflict-related and deactivation of memory-related brain regions. These results are consistent with the hypothesis that during repression, explicit memory systems are down-regulated by the anterior cingulate cortex.
authors: Department of Epileptology, University of Bonn, Bonn, Germany.
authors: Jo-Birger
authors: JB
authors: Schmeing
authors: Aram
authors: A
authors: Kehyayan
authors: Henrik
authors: H
authors: Kessler
authors: Anne T A
authors: AT
authors: Do Lam
authors: Juergen
authors: J
authors: Fell
authors: Anna-Christine
authors: AC
authors: Schmidt
authors: Nikolai
authors: N
authors: Axmacher
mesh_terms: D000328:Adult; D001921:Brain / Q000033:anatomy & histology / Q000502:physiology*; D003220:Conflict, Psychological; D005260:Female; D005608:Free Association; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D011930:Reaction Time; D012094:Repression, Psychology; D055815:Young Adult
references: Nat Rev Neurosci. 2002 Jun;3(6):453-62
references: 12042880
references: Psychophysiology. 2007 May;44(3):343-51
references: 17433093
references: Trends Cogn Sci. 2005 May;9(5):242-9
references: 15866151
references: Nature. 1998 Aug 20;394(6695):787-90
references: 9723618
references: J Abnorm Soc Psychol. 1961 Jan;62:99-105
references: 13761520
references: J Neurosci Methods. 2010 Jun 30;190(1):80-91
references: 20451556
references: Biol Psychiatry. 2004 Mar 15;55(6):603-11
references: 15013829
references: J Clin Endocrinol Metab. 1997 Jul;82(7):2070-5
references: 9215274
references: Mem Cognit. 1990 Sep;18(5):496-506
references: 2233262
references: Proc Natl Acad Sci U S A. 2004 Mar 2;101(9):3310-5
references: 14981255
references: J Exp Psychol Learn Mem Cogn. 1992 Mar;18(2):379-90
references: 1532823
references: J Neurosci. 2005 Sep 14;25(37):8402-6
references: 16162922
references: Memory. 2007 Apr;15(3):227-48
references: 17454661
references: Cogn Affect Behav Neurosci. 2003 Sep;3(3):207-33
references: 14672157
references: J Exp Psychol Gen. 2000 Jun;129(2):242-61
references: 10868336
references: Nat Rev Neurosci. 2010 Jul;11(7):523-32
references: 20531422
references: Science. 2004 Jan 9;303(5655):232-5
references: 14716015
references: Trends Cogn Sci. 2006 Feb;10(2):59-63
references: 16406760
references: Q J Exp Psychol A. 2005 Feb;58(2):193-233
references: 15903115
references: Science. 2007 Jul 13;317(5835):215-9
references: 17626877
references: Life Sci. 1996;58(17):1475-83
references: 8622574
references: J Am Psychoanal Assoc. 1993;41(1):63-93
references: 8426058
references: Behav Brain Res. 2009 Jun 8;200(1):1-6
references: 19373976
references: Prog Brain Res. 2000;126:29-37
references: 11105637
references: Nat Neurosci. 2000 Apr;3(4):313-4
references: 10725918
references: Cogn Affect Behav Neurosci. 2006 Jun;6(2):152-6
references: 17007235
references: Cereb Cortex. 2008 Mar;18(3):670-82
references: 17617657
references: Front Hum Neurosci. 2010 Nov 22;4:211
references: 21151366
references: Prog Brain Res. 2005;150:309-29
references: 16186033
references: Psychol Psychother. 2007 Sep;80(Pt 3):355-66
references: 17877861
references: Trends Cogn Sci. 2011 Feb;15(2):85-93
references: 21167765
references: PLoS One. 2011 Mar 09;6(3):e17635
references: 21408006
references: Psychother Psychosom Med Psychol. 1999 Feb;49(2):64-7
references: 10098394
references: Trends Cogn Sci. 2012 Jan;16(1):6-8
references: 22153583
references: Cereb Cortex. 2010 Feb;20(2):383-92
references: 19505993
references: Neurochem Res. 2003 Nov;28(11):1735-42
references: 14584827
references: PLoS One. 2011 Jan 25;6(1):e15712
references: 21283580
references: Curr Opin Neurobiol. 2004 Apr;14(2):198-202
references: 15082325
references: Neuropsychologia. 2007 Jun 18;45(11):2608-20
references: 17499318
references: Psychol Med. 2006 Jun;36(6):845-56
references: 16704749
references: Annu Rev Neurosci. 2007;30:123-52
references: 17417939
references: Annu Rev Neurosci. 2004;27:279-306
references: 15217334