Type of Publication: | Dissertation |
URI (citable link): | http://nbn-resolving.de/urn:nbn:de:bsz:352-opus-16300 |
Author: | Saleptsi, Evangelia |
Year of publication: | 2005 |
Title in another language: | MEG-Korrelate affektiver Stimulusverarbeitung bei Posttraumatischer Belastungsstörung |
Summary: |
In the present thesis, study I focuses on the relationship between retrospectively reported childhood experiences and psychiatric diagnoses in adult life, study II and study III covers a wide range of affective stimuli and procedures focusing on special features of emotional processing in PTSD: we implemented a visual paradigm to investigate cortical activation patterns during processing of high arousing (pleasant and unpleasant) as compared to low (neutral) arousing pictures in PTSD patients, in schizophrenia patients and healthy controls using magnetoencephalography; in addition to magnetocortical data we examined subjective ratings, heart rate and startle responses. In studies II and III, standardized colored picture stimuli from the International Affective Picture Systems are used. The neural processing underlying emotional information processing in PTSD patients, in schizophrenia patients and healthy participants is studied and the origin of neuromagnetic activity in the brain is modeled by means of magnetic source imaging (MSI). PTSD patients showed a differential sensitivity for the early time windows for high arousing unpleasant pictures. Avoidance symptoms in PTSD patients were negatively correlated with the difference unpleasant minus neutral for the N1m time window suggesting that amplified responses for neutral pictures were negatively correlated with high avoidance scores. PTSD patients showed for the late components increased activity for high arousing pictures suggesting cortical facilitation in attentional processes. Heart rate responses differed significantly among PTSD patients, schizophrenia patients and control participants showing sustained heart rate acceleration for high arousing unpleasant pictures in PTSD patients. Taken together, the earlier amplification for neutral pictures in PTSD patients such as found in the range of the N1m component may indicate initial cortical inhibition of magnetic fields for visual features that are motivationally significant may be associated with PTSD symptoms. As evidenced by the MNE, high arousing pictures elicited greater activity than low arousing (neutral) pictures did in PTSD patients over frontal and frontoparietal cortical networks for the early P3m window, over anterior and posterior parietal regions for the late P3m window and hereby representing differences among groups. There was evidence of failure in PTSD patients but not in schizophrenia patients to show a specific sensitivity to emotional modulation of visual cortex in the range of the N1m time window. Furthermore, source space projection from subsequent time windows such as early and late P3m revealed specific enhancement of electro-cortical activity in PTSD over prefrontal and parietal cortical areas. This finding may reflect increased allocation of attentional resources to arousing stimuli over time in PTSD patients. Based on these observations elements of a model of human emotional stimulus processing in PTSD is proposed.
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Summary in another language: |
Das Betrachten affektiver Reize löst eine Reihe typischer behavioraler, kognitiver und physiologischer Antworten aus. Die Präsentation affektiver Bilder ist daher eine bewährte Methode zur Untersuchung abweichender affektiver Verarbeitung bei emotionalen Störungen.
Die vorliegende Arbeit setzt sich mit den kortikalen Reaktionen auf angenehme, unangenehme (traumabezogenene) und neutrale affektive Bilder des International Affective Picture Systems (IAPS) mittels Magnetoenzephalographie (MEG) auseinander. Drei Gruppen wurden untersucht: 15 Folteropfer, die, die Kriterien einer posttraumatischen Belastungsstörung (PTBS) erfüllten; 15 Patienten mit schizophrenen Störungen; sowie 12 Kontrollpersonen. Die magnetischen Antworten zeigten keine Unterschiede zwischen schizophrenen Patienten und Kontrollpersonen in den frühen Verarbeitungsprozessen. Für Patienten mit einer PTBS wurde dagegen eine perzeptuelle Erleichterung neutraler Bilder und eine Hemmung unangenehmer Bilder nachgewiesen (N1m Komponente). Ebenso zeigten PTBS-Patienten erhöhte Schreckreflexamplituden und erhöhte Herzraten beim Betrachten angstbesetzter Stimuli. Die späteren Verarbeitungsprozesse konnten in einer anderen Weise differenziert werden. PTBS-Patienten zeigten eine spätere spezifische Erhöhung der Amplitude auf aversive Stimulation sowohl für die frühe P3m als auch für die spätere P3m Komponente. Insbesondere diese affektiven Modulationen wurden auch im Quellenraum nachgewiesen: für frühere Prozesse zeigten PTBS-Patienten eine Hemmung im visuellen Kortex in der Merkmalsverarbeitung traumabezogener Bilder. Die Schwerpunkte der Aktivierung für spätere Komponenten bei PTBS-Patienten (early P3m, late P3m) wurden vor allem an präfrontalen und parietalen kortikalen Hirnarealen identifiziert. Dagegen zeigten schizophrene Patienten und Kontrollpersonen für spätere Prozesse eine Aktivierung in visuellen und in parietalen kortikalen Hirnarealen. Diese Befunde legen nahe, dass PTBS-Patienten die unangenehmen Bilder bereits in der frühen Merkmalsanalyse in visuellen Hirnarealen unterdrücken. In späteren Verarbeitungsschritten, die bei Kontrollpersonen und schizophrenen Patienten von visuellen und parietalen Hirnarealen ausgeführt werden, aktivieren PTBS-Patienten ein präfrontales Furchtnetzwerk für alle erregende Bilder. Auf Grundlage dieser Befunde wird ein Model der affektiven Verarbeitung bei der PTBS entwickelt. |
Examination date (for dissertations): | Sep 13, 2005 |
Dissertation note: | Doctoral dissertation, University of Konstanz |
Subject (DDC): | 150 Psychology |
Controlled Keywords (GND): | Magnetoencephalographie, Posttraumatisches Stresssyndrom, Psychisches Trauma |
Keywords: | Herzrate, Schreckreflex, Posttraumatische Belastungsstörung, Schizophrenie, Emotion, Magnetoencephalography, Heart Rate, Posttraumatic Stress Disorder, Schizophrenia, Emotion |
Link to License: | In Copyright |
SALEPTSI, Evangelia, 2005. MEG Correlates during Affective Stimulus Processing in Posttraumatic Stress Disorder [Dissertation]. Konstanz: University of Konstanz
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