Contextual modulation during processing of facial expressions [Elektronische Ressource] : behavioral, fMRI and ERP investigations / vorgelegt von Sascha Frühholz

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• Publié par: universitat_bremen
• Publié le: 01 janvier 2008
• Nombre de lectures: 111
• Poids de l'ouvrage: 2 Mo

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Aus der
Abteilung für Neuropsychologie und Verhaltensneurobiologie
Zentrum für Kognitionswissenschaften (ZKW)
»Contextual Modulation During Processing
of Facial Expressions. Behavioral, fMRI and
ERP Investigations.«
Dissertation
zur Erlangung des Grades eines
Doktors der Naturwissenschaften (Dr. rer. nat.)
vorgelegt von:
Sascha Frühholz
aus Augsburg
dem
Fachbereich 2 (Biologie/Chemie) der Universität Bremen
1. Gutachter: Prof. Dr. med. Dr. phil. Manfred Herrmann
2. Gutachter: Prof. Dr. rer. nat. Dr. phil. Gerhard Roth
Tag der mündlichen Prüfung: 15.09.2008 PELLÉAS: »… Qu'as-tu donc? Tu ne me
sembles pas heureuse …« -
MÉLISANDE: »Si, si, je suis bien heu-
reuse, mais je suis triste …«.
PELLÉAS: »... Was ist dir? Sage doch,
bist du denn nicht glücklich ...« -
MÉLISANDE: »Doch doch, ja, ich bin
glücklich, doch ich bin traurig ...«.
Claude Debussy / Maurice Maeterlinck
Pelléas et Mélisande, IV, 4. Summary
Page
I Introduction: The emotional face in
context 13
1.1 Preferential processing of emotional facial expressions 15
1.2 Contextual influences and interference resolution during emotional
face processing 17
1.2.1 Evidence from behavioral studies 18
1.2.2 functional imaging studies 20
1.2.3 Evidence from electrophysiological studies 22
1.3 Aims and scope of the present studies 24
II Methods 26
2.1 Behavioral correlates of emotional interference 27
2.2 Functional magnetic resonance imaging (fMRI) 28
2.2.1 Data acquisition 29
2.2.2 Data analysis 30
2.3 Event-related potentials (ERP) in the electroencephalogram (EEG) 31
2.3.1 Data acquisition 32
2.3.2 Data analysis 32
2.4 Experimental procedure: Study design and strategies of data analyses 33
2.4.1 Stimuli 33
2.4.2 Trials and sequence 34
2.5 Data protection, data security and legal framework 35 III Empirical studies 37
3.1 Conflicting contextual features disturb fast valence judgments of
facial affect 38
3.1.1Introduction 38
3.1.2 Materials and methods 39
3.1.2.1 Participants 39
3.1.2.2 Stimuli and experimental procedure 39
3.1.3 Results 41
3.1.4 Discussion 43
3.1.4.1 Dissociation of incongruent trials with negative
expression 44
3.1.4.2 Differential effects of interference depending on the
valence of facial expressions 44
3.1.4.3 Limitations of the present study and final remarks 48
3.2 Brain regions responsible for conflict resolution depend on the
valence of facial affect 50
3.2.1Introduction 50
3.2.2 Materials and methods 51
3.2.2.1 Participants 51
3.2.2.2. Stimuli and experimental task 51
3.2.2.3 Statistical analysis 52
3.2.3 Results 54
3.2.3.1 Behavioral data 54
3.2.3.2 Imaging data 55
3.2.4 Discussion 57
3.2.4.1 Frontal, parietal and ventral systems of attentional
control 59
3.2.4.2 A selective attention network 60
3.2.4.3 Regions exclusively activated in emotional
interference processing 61
3.2.4.4 Conclusive remarks 63 3.3 Trait dimensions of personality influence emotional conflict
processing – evidence from fMRI 65
3.3.1Introduction 65
3.3.1.1 Personality traits and the resolution of emotional
conflict during face processing 66
3.3.1.2 Encoding style as perceptual trait 67
3.3.2 Materials and method 69
3.3.2.1 Participants 69
3.3.2.2 Stimuli and experimental task 70
3.3.2.3 Statistical analysis
3.3.3Results 72
3.3.3.1 State and trait measures of personality and
encoding style 72
3.3.3.2 Behavioral data 73
3.3.3.3 Imaging data 75
3.3.4Discussion 79
3.3.4.1 Dimensions of personality as trait markers of
differential emotional interference processing 79
3.3.4.2 Individual encoding style influences the degree of
conflict adjustment during emotional interference
processing 82
3.4 Dissociative temporal stages for detection and resolution of conflicts
during processing of facial affect 85
3.4.1Introduction 85
3.4.2 Materials and methods 86
3.4.2.1 Participants 86
3.4.2.2 Stimuli and experimental task 86
3.4.2.3 Statistical analysis 87
3.4.3 Results 89
3.4.3.1 Behavioral data 89
3.4.3.2 ERP data 90
3.4.3.3 Source localization 933.4.4 Discussion 94
3.4.4.1 Behavioral correlates of contextual interference 94
3.4.4.2 Effects of emotional context information on early
ERP components 95
3.4.4.3 ERP components of interference processing 98
3.4.4.4 Conclusions 100
IV General discussion and conclusion 101
4.1 General effects of contextual interference 102
4.2 Expression specific effects of contextual interference 104
4.3 Individual differences in contextual interference resolution 106
4.4 Emotional face processing is not entirely automatic 109
References 112
List of Figures 136
List of Tables 137
Appendix 139 Acknowledgments
I would like to thank my supervisors Manfred Herrmann and Thorsten Fehr for their
enduring support and advice during all the time of my Ph.D. project. I also thank
Gerhard Roth for his willingness to figure as reviewer for this dissertation.
I am also thankful to my colleagues Sina Trautmann, Daniala Galashan, Stephan Miedl
as well as Peter Erhard, Ekkehard Küstermann, Judith Domínguez Borràs and Carles
Escera for valuable discussions and for their helpful comments on uncountable
questions and problems. I also thank Charlotte Giessmann for helpful comments on the
manuscript.
Finally, I thank all students who did an internship or a diploma thesis at the Department
and who gave me indispensable support during conductance and data analysis of the
studies.Abstract
Facial expressions of emotions are assumed to be processed rapidly and automatically
and therefore should be immune to simultaneous task induced interference. Recent
functional and electrophysiological studies however reported that contextual features
modulate the processing of emotional expressions when presented in the temporal and
spatial context of these expressions. Therefore, additional contextual features which
specifically signal incongruent emotional information compared to task-relevant facial
expressions might introduce an emotional ambiguity during the recognition of these
expressions and thereby interfere with their automatic processing.
A behavioral, a functional MRI and an electrophysiological study were conducted to
examine the impact of a low-level and an emotional associated contextual feature on
fast valence categorizations of facial expressions. In each study, subjects incidentally
learned to perceive negative, neutral and positive facial expressions within a specific
colored context in a first experimental run. In the following experimental run subjects
were asked for fast valence judgments while presented with expression-color-
combinations as in the first run (congruent trials) or with systematic variations of these
expression-color-combinations (incongruent trials).
Emotional conflicting information during the evaluation of facial expressions induced
significant effects of interference indicated by prolonged response times and a decrease
in response accuracy in the initial behavioral study. Emotional incongruent trials
revealed differential effects depending on the emotional valence of the facial
expression. Especially for positive expressions fast valence categorization in congruent
trials might likewise indicate effects of facilitation.
Incongruent trials induced activations in a common fronto-parietal selective attention
network in the fMRI study. Whereas incongruent trials with neutral expressions
revealed distinct activations in regions particularly involved in processing both the task-
relevant facial expressions and the task-irrelevant color, incongruent trials with positive
facial expressions revealed only sparse activation in the frontal cortex. Contextual
interference resolution during processing of negative facial expressions resulted in
specific activation in regions which might be involved in implicit morphological
dynamics of facial displays. A subsequent differential analysis of the fMRI data revealed widespread activations for
task induced incongruence for subjects scoring high on neuroticism, anxiety and
depressivity but also for subjects with an internal encoding style. Neurotic and anxious
subjects have been previously shown to exhibit a neuronal dysregulation during
emotional processing and emotional conflict resolution. Internal encoders strongly rely
on their formerly learned schema of face-color-combination. When confronted with
incongruent trials in the second experimental run, internal encoders must recruit
increased processing resources to overcome their contextually instantiated and schema
induced conflict.
In the final ERP study, contextual interference during processing of neutral expressions
confirmed early activation in occipito-temporal areas most likely involved in elaborated
face processing. Differential modulatory effects during emotional face perception
revealed early sensitivity within 280ms poststimulus to task-relevant and task-irreleva