Influence of Repressive Coping Style on Cortical Activation during Encoding of Angry Faces

21 Pages·2014·0.28 MB·English

RESEARCHARTICLE
Influence of Repressive Coping Style on
Cortical Activation during Encoding of
Angry Faces
AstridVeronikaRauch1*,LenaterHorst1,VictoriaGabrielePaul1,JochenBauer1,
Udo Dannlowski2, Carsten Konrad2, Patricia Ohrmann1, Harald Kugel3,
Boris Egloff4, Volker Arolt1, Thomas Suslow5
1.DepartmentofPsychiatry,UniversityofMuenster,Muenster,Germany,2.DepartmentofPsychiatry,
UniversityofMarburg,Marburg,Germany,3.DepartmentofClinicalRadiology,UniversityofMuenster,
Muenster,Germany,4.DepartmentofPsychology,UniversityofMainz,Mainz,Germany,5.Departmentof
PsychosomaticMedicine,UniversityofLeipzig,Leipzig,Germany
*[email protected]
Abstract
Background: Coping plays an important role for emotion regulation in threatening
situations. The model of coping modes designates repression and sensitization as
two independent coping styles. Repression consists of strategies that shield the
individual from arousal. Sensitization indicates increased analysis of the
OPENACCESS
environment in order to reduce uncertainty. According to the discontinuity
Citation:RauchAV,terHorstL,PaulVG,BauerJ,
hypothesis, repressors are sensitive to threat in the early stages of information
DannlowskiU,etal.(2014)InfluenceofRepressive
CopingStyleonCorticalActivationduring processing. While repressors do not exhibit memory disturbances early on, they
EncodingofAngryFaces.PLoSONE9(12):
manifest weak memory for these stimuli later. This study investigates the
e112398.doi:10.1371/journal.pone.0112398
discontinuity hypothesis using functional magnetic resonance imaging (fMRI).
Editor:LindaChao,UniversityofCalifornia,San
Francisco,UnitedStatesofAmerica Methods: Healthy volunteers (20 repressors and 20 sensitizers) were selected
Received:September7,2012 from a sample of 150 students on the basis of the Mainz Coping Inventory. During
Accepted:October16,2014 the fMRI experiment, subjects evaluated and memorized emotional and neutral
Published:December11,2014 faces. Subjects performed two sessions of face recognition: immediately after the
Copyright:(cid:2)2014Rauchetal.Thisisanopen- fMRI session and three days later.
accessarticledistributedunderthetermsofthe
Results: Repressors exhibited greater activation of frontal, parietal and temporal
CreativeCommonsAttributionLicense,which
permitsunrestricteduse,distribution,andrepro- areas during encoding of angry faces compared to sensitizers. There were no
ductioninanymedium,providedtheoriginalauthor
differences in recognition of facial emotions between groups neither immediately
andsourcearecredited.
after exposure nor after three days.
Funding:TheDeutscheForschungsgemeinschaft
(DFG)supportedpartofthisresearch(RA2009/1- Conclusions: The fMRI findings suggest that repressors manifest an enhanced
2).Thefundershadnoroleinstudydesign,data
collectionandanalysis,decisiontopublish,or neural processing of directly threatening facial expression which confirms the
preparationofthemanuscript.Noadditional
assumption of hyper-responsivity to threatening information in repression in an
externalfundingwasreceivedforthisstudy.
early processing stage. A discrepancy was observed between high neural
CompetingInterests:Theauthorshavedeclared
thatnocompetinginterestsexist.
PLOSONE | DOI:10.1371/journal.pone.0112398 December11,2014 1/21
CopingStyleandEncodingofAngryFaces
activationinencoding-relevantbrainareasinresponsetoangryfacesinrepressors
and no advantage in subsequentmemory for these faces compared to sensitizers.
Introduction
Coping is the process of attempting to manage the demands created by stressful
events [1]. Coping strategies can be adaptive or maladaptive. The development of
psychiatric diseases and the maintenance of physical health is influenced by
coping, which can also influence interventions by aiming to reduce the health
risks of stress [2]. Therefore, knowledge about coping is important for developing
a better understanding of psychiatric diseases.
The model of coping modes [3,4] describes habitual behavior tendencies in
reaction to anxiety-provoking and threatening situations. Referring to this model,
the terms ‘repression’ and ‘sensitization’ are introduced as independent coping
styles. Repression ischaracterized bycognitive avoidance ofthreatening stimuli in
order to shield the organism from distressing stimuli and to prevent an
uncontrollable increase in arousal. The behavioral aim of repressors is to divert
attention from threat-relevant cues. In contrast, sensitization is associated with
vigilance and the ability to tolerate arousal but not uncertainty.
Although repressors describe themselves as low-anxious, they exhibit higher
than average levels of physiological arousal [5–7] and are at an increased risk of
stress related health problems [8]. The use of avoidant coping strategies is
associated with a worse outcome in depression and several somatic diseases (for a
review, see [2]).
Previous coping studies have revealed several differences in memory processing
for emotional stimuli. Generally, repressors tend to avoid threats in order to
prevent arousal, but the repressive discontinuity hypothesis postulates that, when
exposed, repressors are not generally insensitive to threat at an early stage of
memory processing. Instead, repressors showed a decline in memory for
threateningstimuliafter3days,butnotduringimmediaterecall(30 minutesafter
stimulus exposure) [9,10]. However, the discontinuity hypothesis has not been
tested in the context of neuroimaging. Thus, the cerebral correlates of encoding
remain unclear in repression.
Only a few imaging studies have investigated emotion processing in repression.
Sander et al. [11] found an increased activation in repressors in left
temporoparietal regions during the presentation of sad intonations. Cortical
activation was also found to be larger for repressors in prefrontal areas. In a
previous study [12] we demonstrated that repressors showed heightened
activation in frontal and temporo-occipital areas during the perception of fearful
and happy faces. Repressors exhibited an increased connectivity between medial
prefrontal areas and the amygdala during the presentation of fearful faces.
PLOSONE | DOI:10.1371/journal.pone.0112398 December11,2014 2/21
CopingStyleandEncodingofAngryFaces
Facial expressions play an important role in social signaling and for
determiningenvironmentalconditions[13,14].Correctlyinterpretingthreatening
faces is crucial for detecting environmental danger. So far, emotional faces have
not been applied to test the discontinuity hypothesis. Hence, we employed
emotional faces in this context. In the past, several functional magnetic resonance
imaging (fMRI) studies investigated emotional face processing. Increased
activation during the processing of emotional faces was found in several regions,
including prefrontal, temporoparietal, limbic, visual areas, amygdala, putamen
and cerebellum ((for reviews see [15–17]). A recent study [18] investigated
memory for emotional stimuli and revealed several areas that were involved in
recognizingemotionalfaces.Theseincludedprefrontalandfrontalregions,aswell
as temporal and parietal areas. Encoding of emotional faces was associated with
activity in the dorsolateral prefrontal cortex (DLPFC), frontal areas, amygdala,
temporo-occipital regions and parietal lobule [19,20].
Taken together,the neurobiological mechanisms ofthe repressive discontinuity
hypothesis in the context of processing emotional faces remain unknown.
Therefore,theaimofthisfMRIstudyistotestthishypothesisataneurobiological
level. Repressors are expected to evaluate emotional faces as less threatening than
sensitizers. Based on previous studies it is hypothesized that repressors will show
anincreased response tothreateningfaces (i.e.angryandfearfulfacialexpression)
in cortical regions which are known to play a role in emotion regulation and
memory encoding, such as the prefrontal and temporo-parietal areas. Therefore,
repressors’ memory for threatening faces should be better directly after encoding
compared to that of sensitizers. Furthermore, it was hypothesized that due to
cognitive avoidance repressors will show a decreased memory for threatening
faces after three days compared to sensitizers.
Methods
Participants
Forty healthy female, right-handed university students participated in this fMRI
study. All subjects had no history of psychiatric, neurological, or other relevant
medical diseases, were free of psychotropic medication and had a normal or
corrected-to-normal (by contact lenses) vision. Handedness was assessed with the
HandednessQuestionnaire[21].VisualacuitywascheckedpriorthefMRIsession
by reading a miniature Snellen eye chart. Study participants were selected from a
sample of 150 students on the basis of their scores on the German version of the
Mainz Coping Inventory, MCI [22]. Twenty persons with high scores on the
cognitive avoidance scale (.66th percentile of the screening sample) and low
scores on the vigilance scale (,33th percentile) were included as consistent
repressors in the present study, whereas 20 persons with high scores on the
vigilance scale (.66th percentile of the screening sample) and low scores on the
cognitive avoidance scale (,33th percentile) were included as consistent
sensitizers. Cronbach’s a was 0.84 for the MCI avoidance scale and 0.89 for the
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CopingStyleandEncodingofAngryFaces
Table1.Descriptivecharacteristicsofstudyparticipants.
Sensitizers Repressors
Mean SD Mean SD
MCIvigilance 28.2 3.3 14.0 2.7
MCIcognitiveavoidance 16.5 4.1 27.5 2.4
Age 22.9 2.3 22.4 2.7
VerbalIQ(MWT-B) 115.8 10.9 117.0 13.0
PictureCompletion(WAIS-R) 14.5 1.3 14.2 1.9
STAI-State 36.0 6.7 31.6 4.7
STAI-Trait 36.1 8.7 29.2 4.2
BDI 3.9 4.7 2.0 2.0
Note.MCI:MainzCopingInventory;WAIS-R:WechslerAdultIntelligenceScale–revisedform;STAI:State-TraitAnxietyInventory,stateandtraitversion;
BDI:BeckDepressionInventory.
doi:10.1371/journal.pone.0112398.t001
MCI vigilance scale. Repressors differed significantly (Ps,0.001) from sensitizers
on both MCI scales (see table 1). Subjects were screened for imaging safety
concerns, and gave written informed consent, which was approved by the ethics
committee of the Medical Faculty at the University of Muenster. All subjects
received a compensation of 35 EUR after their participation. The same subjects
participated also in a second experiment which was published previously [23]. In
thisexperimentadetection task wasapplied tomeasure automaticresponsivityto
facial emotions as a function of coping style. The detection task was always
conductedbeforethepresentmemoryexperimentanduseddifferentfacialstimuli
[24]. In the detection task participants were shown happy, angry, fearful, and
neutral facial expressions masked by neutral faces and they had to guess which of
these facial expressions has been briefly presented [23].
Questionnaires and Neuropsychological Measures
TheMCI[25]isastimulus-response inventorythatassessesvigilantandcognitive
avoidant coping strategies in 4 ego-threatening (e.g., public speaking) and 4
physically threatening situations (e.g., riding with an inexperienced driver). For
each situation, 5 vigilant or sensitizing items (e.g., information search,
anticipation of negative events) and 5 cognitively avoidant or repressive items
(e.g., denial, attention diversion) are administered in a true—false response
format. Scored answers are summed for vigilant and avoidant items across all 8
situations.
The State-Trait Anxiety Inventory, STAI, [26] was administered in its German
version[27],aswellastheBeckDepressionInventory,BDI,[28,29].TheMultiple
choice vocabulary test, MWT-B, [30] was applied to assess the verbal intelligence
of study participants. Picture Completion is a subtest of the Wechsler Adult
Intelligence Scale, WAIS-R, [31] which measures visual perception and
recognitionofessentialdetailsofobjects.Statisticalanalyseswereperformedusing
SPSS Statistics 17.0.0 (Statistical Package for the Social Sciences, 2008).
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CopingStyleandEncodingofAngryFaces
fMRI Stimulus Material and Procedure
The study protocol included an event-related fMRI experiment and two sessions
of face recognition tasks outside the scanner after the fMRI session. The first was
30 minutes after, and the second 3 days after. All three tasks included colored
facial stimuli (angry, happy, fearful and neutral) [32] of 15 male and 15 female
subjects. Facial stimuli were presented pseudo-randomly. Only during the fMRI
experiment was a no face condition (a grey rectangle) added to optimize the
paradigmwithnullevents[33].InthefMRIexperiment,150trialswerepresented.
Each emotional face condition and the no face condition consisted of 30 trials.
Thetotaldurationoftheexperimentwas17.5 minutes.Afixationcrossof500 ms
preceded the emotion face, which was presented for 3000 ms followed
immediately by a time interval (3500 ms) for rating the facial emotion as rather
threatening (20.5, 21.5) or rather non-threatening (+0.5, +1.5) by pressing a
button. Thus, both negative numbers were accompanied by the adjective
‘‘threatening’’, whereas both positive numbers were accompanied by the adjective
‘‘non-threatening’’. One-half of the samples gave positive responses with the left
hand and the other half used the right hand for positive responses. Subjects were
instructed to evaluate and memorize the faces. The experiment was programmed
usingthesoftwarepackageInquisit[34].Twofixedrandomorderswerepresented
which were counterbalanced across subjects. The type of evaluative response and
reaction latencies were registered. Face stimuli were presented via a projector
(Sharp XG-PC10XE). The head position was stabilized with a vacuum head
cushion.
The two recognition tasks consisted of 120 original faces shown during the
fMRI session and 120 distractors (30 angry, 30 happy, 30 fearful and 30 neutral
facesof other individuals [32]).Twofixedrandomordersof faceswerepresented.
The order of faces was counterbalanced across subjects. Subjects were instructed
to rate whether they have seen the faces during the fMRI experiment or not.
Participants rated the facial emotion as original seen during the fMRI session
(‘‘Yes’’) or as distractors (‘‘No’’) by pressing a button. Each stimulus was
presented until the subject responded.
fMRI Data Acquisition and fMRI Data Analyses
T * functional data were acquired at a 3-Tesla scanner (Gyroscan Intera 3T,
2
Philips Medical Systems, Best, The Netherlands) using a single shot echoplanar
sequence with parameters selected to minimize distortion while retaining
adequate signal to noise ratio and T * sensitivity, according to suggestions made
2
by Robinson et al. [35]. Volumes consisting of 36 axial slices were acquired
(matrix 642, resolution 3.5 mm * 3.5 mm * 3.5 mm; time repetition 52.5 s, time
echo 535 ms, flip angle 590˚) 420 times in an event-related design. T -weighted
1
inversion recovery and a high-resolution T -weighted 3D sequence (isotropic
1
pixel, 0.53 mm) were also acquired. Functional imaging data were motion
corrected using a set of 6 rigid body transformations determined for each image.
We applied slice timing and images were spatially normalized to standard MNI
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CopingStyleandEncodingofAngryFaces
space (Montreal Neurological Institute) as well as smoothed (Gaussian kernel, 6-
mm FWHM) using Statistical Parametric Mapping 5 (SPM5; Wellcome
Department of Cognitive Neurology, London, UK, http://www.fil.ion.ucl.ac.uk/
spm)implementedinMatlab7.1.Checksonmotionartifactswereperformedand
analyses used the estimated motion parameters as covariates of no interest in the
event related design matrix. Statistical analysis was performed by modeling the
different conditions (angry, fearful, happy, and neutral) as variables within the
context of the general linear model.
A whole-brain analysis was conducted to determine which brain regions were
differentially activated as a function of coping style. For each emotion condition
(fearful, angry, and happy), activation data (t maps) were calculated for subjects
relative to the neutral control face condition. Furthermore, activation data of the
neutral versus angry contrast were calculated for each subject. Random effects
analysis (t-tests for independent samples) was performed to examine brain
activation differences between groups (on the contrasts: fearful vs. neutral, angry
vs. neutral, happy vs. neutral and neutral vs. angry). Coordinates of significant
activations (p,0.05, k550, False Discovery Rate) were converted into Talairach
and Tournoux [36] space using the Talairach Daemon [37].
Results
Questionnaires and Neuropsychological Measures
Repressors and sensitizers did not differ in mean age, verbal intelligence 29 or
visual perception and organization ((WAIS-R, (Ps.0.53)). Cronbach’s a for the
STAI state version was 0.86. Sensitizers were more anxious than repressors (t (38)
522.42, P,0.05). Cronbach’s a for the STAI trait was 0.92. As expected,
sensitizers had higher trait anxiety scores than repressors (t (38) 523.16,
P,0.005). Cronbach’s a for the BDI was 0.83. Sensitizers and repressors did not
differ on the BDI (P.0.10) (see table 1).
Behavioral Performance
We conducted t-tests for sum scores of evaluation ratings and latencies for all
facial conditions (fearful, angry, happy, and neutral). Only ratings for the neutral
faceconditionshowedasignificantdifferencebetweenrepressorsandsensitizers(t
(38) 52.10, p50.042), but not for latency (t (38) 51.69, p50.20). Repressors
rated neutral faces as less threatening than sensitizers. Repressors tended to rate
angry (t (38) 51.59, p50.12) and fearful (t (38) 51.46, p50.15) faces as less
threatening than sensitizers, but these results, as for happy faces (t (38) 50.11,
p50.92),didnotreachstatisticalsignificance.Inallconditions,sensitizersshowed
longer latencies than repressors, but differences were not significant (see table 2).
To examine the influence of coping on recognition memory, we carried out
26264ANOVAswithgroupasbetween-groupindependentvariableandtimeof
recall(immediatevs.delayedrecall)andfacecondition(fearful,angry,happy,and
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CopingStyleandEncodingofAngryFaces
Table2.Faceevaluationtask(fMRIexperiment):evaluativeratingsandlatenciesasafunctionoffacialexpressionandcopingstyle(lowvaluesindicate
moreperceivedthreat).
Sensitizers Repressors
Mean SD Mean SD
Angryfaces
Rating 20.9 0.3 20.6 0.6
Latency 639.3 221.4 603.3 158.7
Happyfaces
Rating 1.3 0.3 1.3 0.4
Latency 583.8 205.3 526.3 143.3
Fearfulfaces
Rating 20.2 0.4 0.0 0.7
Latency 617.9 230.4 544.1 147.1
Neutralfaces
Rating 0.3 0.3 0.5 0.5
Latency 587.64 205.6 514.4 145.1
doi:10.1371/journal.pone.0112398.t002
neutral) as repeated measure independent variables. First, we analyzed total
numbers of correctly remembered original faces (hits). There were main effects of
time (F (1,38) 516.87, p,0.001) and emotion (F (3,36) 54.10, p50.013) for
correctly recognized original faces. Subjects showed significantly more hits in the
immediate than in the delayed recognition task and the most hits for the happy
condition. No effects involving groups were found in the hit condition. Second,
analysisoffalsepositivelyidentifieddistractorsdidnotrevealamaineffectfortime
or group, buta main effect for emotion was observed(F (3,36)510.29,p,0.001).
According to the results of paired t-tests, subjects produced more false alarms for
happyandangryfacescomparedtoneutralfaces(p,0.05)(seetable 3fordetails).
Additionally,weassessedparticipants’discriminationperformancebycalculatinga
discriminationindexH-FA(hitrate(numberofhits/30)–falsealarmrate(number
offalsealarms/210))(seetable 4).TheANOVAresultsbasedonthediscrimination
index showed significant main effects of time (F (1,38) 518.88, p,0.001) and
emotion(F(3,36)53.82,p50.018).Participantsmanifestedabetterdiscrimination
performanceimmediatelyafterthefMRIexperimentcomparedtothedelayedrecall
conditionandrecognizedhappyfacesbetterthanneutralfaces.Noeffectsinvolving
groups were observed for the discrimination index.
Whole Brain FMRI Results: Between Group Comparison
Brain response to angry faces compared to neutral faces
Repressors showed greater activation in the superior, medial, middle and inferior
frontalgyrus,superiortemporalgyrus,precuneus,cerebellum,andinferiorparietal
lobe relative to sensitizing individuals. No significantly increased brain activation
wasfoundinsensitizingindividuals.Alldataaresignificantatp,0.05,k550,False
Discovery Rate corrected (FDR). Please see table 5 and Fig. 1 for details.
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CopingStyleandEncodingofAngryFaces
Table3.Immediate(time1)anddelayed(time2)recognitionperformanceasafunctionoffacialexpressionandcopingstyle(numberofcorrectrecognitions
(hits)andfalsealarms).
Sensitizers Repressors
Mean SD Mean SD
Hits
Angrytime1 15.9 5.9 14.9 6.1
Angrytime2 13.0 6.7 12.1 4.2
Happytime1 16.7 6.6 16.0 6.4
Happytime2 14.4 7.3 11.9 5.8
Fearfultime1 15.7 7.1 12.2 5.5
Fearfultime2 13.7 6.9 10.9 4.8
Neutraltime1 13.9 6.9 13.2 5.0
Neutraltime2 12.7 7.6 10.0 4.9
Falsealarms
Angrytime1 7.7 6.8 7.4 4.8
Angrytime2 7.9 7.1 6.9 4.6
Happytime1 7.7 7.7 7.3 6.2
Happytime2 7.7 7.4 6.9 6.3
Fearfultime1 6.0 6.0 5.2 4.8
Fearfultime2 7.3 6.6 5.1 5.0
Neutraltime1 6.2 6.9 5.7 5.3
Neutraltime2 7.0 7.1 5.4 4.2
Note:time15after30minutes;time25after3days.
doi:10.1371/journal.pone.0112398.t003
Table4.Discriminationperformance(H(hitrate(numberofhits/30))–FA(falsealarmrate(numberoffalsealarms/210)))asafunctionoffacialexpression
andcopingstyle.
Sensitizers Repressors
Mean SD Mean SD
H-FAAngrytime1 0.49 0.17 0.46 0.19
H-FAAngrytime2 0.40 0.20 0.37 0.12
H-FAHappytime1 0.52 0.20 0.50 0.20
H-FAHappytime2 0.44 0.22 0.36 0.17
H-FAFearfultime1 0.49 0.22 0.38 0.17
H-FAFearfultime2 0.42 0.21 0.34 0.15
H-FANeutraltime1 0.43 0.21 0.41 0.15
H-FANeutraltime2 0.39 0.23 0.31 0.15
Note:time15after30minutes;time25after3days.
doi:10.1371/journal.pone.0112398.t004
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CopingStyleandEncodingofAngryFaces
Table5.Brainregionswithheightenedactivationofrepressorscomparedtosensitizersintheangryversusneutralfacecontrast.
BrainRegion BAa Hemisphereb MNICoordinates Size Z-scorec
x y z
Inferiorfrontalgyrus 9 R 60 12 28 633 5.06
Medialfrontalgyrus 6 R 10 222 56 153 3.99
Middlefrontalgyrus 46 L 250 32 20 213 3.98
Superiorfrontalgyrus 10 R 30 60 20 64 3.72
Superiortemporalgyrus 39 R 36 260 30 64 3.87
Inferiorparietallobule 40 L 264 230 28 97 3.61
Precuneus 7 L 26 270 48 760 3.94
Cerebellum Declive L 230 260 230 534 3.96
aBrodmannareas.
bL5left,R5right.
cCoordinatesofthemaximalpointofactivationandtheassociatedZ-valuesareshown.Theactivationsaresignificantatp,0.05,k550(FDRcorrected).
doi:10.1371/journal.pone.0112398.t005
Brain response to fearful faces compared to neutral faces
Repressive and sensitizing individuals showed no significant differences in brain
activation (p,0.05, k550, FDR).
Brain response to happy faces compared to neutral faces
No significant differences were found in brain activation between repressive and
sensitizing individuals (p,0.05, k550, FDR).
Brain response to neutral faces compared to angry faces
Sensitizers showed greater activation in the superior, medial, middle and inferior
frontal gyrus, superior, middle and inferior temporal gyrus, fusiform gyrus,
middle occipital gyrus, precentral gyrus, substantia nigra, thalamus,
Fig.1.Between-groupdifferencesinbrainresponsetoangryfacialexpressioncomparedtoneutral
faces.Enhancedbrainactivationsofrepressorscomparedtosensitizers(MNIcoordinates).Theactivations
aresignificantatp,0.05,k550(FDRcorrected).Reader’srightissubjects’right.
doi:10.1371/journal.pone.0112398.g001
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CopingStyleandEncodingofAngryFaces
hippocampus, precuneus, cerebellum, and inferior parietal lobule relative to
repressive individuals. No significantly increased brain activation was found in
repressive individuals. All data are significant at p,0.05, k550, False Discovery
Rate corrected (FDR). Please see table 6 for details.
Correlations between brain response to angry faces with memory for angry
faces
To explore the relationship between activation in those brain areas where
repressorsmanifestedoveractivationcomparedwithsensitizersandrecognitionof
angry faces we calculated for each participant mean activation scores averaged
across all voxels for each of the eight clusters where group differences were
observed. Then Product–moment correlations were calculated between mean
cluster activation scores and memory for angry faces at time 1 and time 2 were
calculated for sensitizers and repressors separately (see Table 7). Even though no
significant correlations betweenbrainresponseandrecognitionperformancewere
found interesting differential correlation patterns were observed. Almost all
correlationsofbrainactivationwithimmediaterecognitionhadapositivesignfor
both study groups. Sensitizers showed also exclusively positive correlations
between brain response and delayed recognition butrepressors manifestedin four
cases negative correlations with delayed recognition for angry faces.
Finally,anindexforlossofdiscriminationaccuracyovertimewascomputedby
subtracting discrimination accuracy at time 2 from discrimination accuracy at
time1(H-FAtime1–H-FAtime2).Sensitizersshowedfivenegativecorrelations
between brain response to angry faces and loss of discrimination accuracy over
time. This means that higher activation in response to angry faces at encoding
tended to be associated with less memory loss for angry faces over time.
Repressors manifested instead exclusively positive correlations between brain
response to angry faces and loss of discrimination accuracy. Thus, for repressors
higher activation in response to angry faces at encoding tended to be related to
more memory loss for angry faces. To compare strength of correlation of brain
response with memory loss between groups Fisher’s Z was applied. For the
correlation betweenmiddle frontal gyrus activation and memory loss a significant
difference between groups was obtained ((z51.64, p50.05, one-tailed). For the
correlations of inferior frontal gyrus and superior temporal gyrus activation with
memory loss marginally significant differences between groups in height of
correlation were observed ((z51.47 and z51.34 p,0.10, one-tailed).
Discussion
The aim of this study was to test the discontinuity hypothesis using fMRI. We
investigated the influence of coping style on brain activation during memory
encoding of emotional faces and the relationship between coping style and the
recall of threatening and non-threatening faces. To date, the discontinuity
hypothesis has been investigated by behavioral studies only.
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