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Associative fear structures in PTSD refugee adolescents : Insights from neurophysiological and behavioral studies

Associative fear structures in PTSD refugee adolescents : Insights from neurophysiological and behavioral studies

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BALLIEL, Britta, 2008. Associative fear structures in PTSD refugee adolescents : Insights from neurophysiological and behavioral studies [Dissertation]. Konstanz: University of Konstanz

@phdthesis{Balliel2008Assoc-10873, title={Associative fear structures in PTSD refugee adolescents : Insights from neurophysiological and behavioral studies}, year={2008}, author={Balliel, Britta}, address={Konstanz}, school={Universität Konstanz} }

2011-03-25T09:23:28Z application/pdf Balliel, Britta Assoziative Furchtstrukturen bei jugendlichen Flüchtlingen mit PTSD - Erkenntnisse aus neurophysiologischen und behavioralen Studien Associative fear structures in PTSD refugee adolescents : Insights from neurophysiological and behavioral studies Attribution-NonCommercial-NoDerivs 2.0 Generic eng 2011-03-25T09:23:28Z Balliel, Britta 2008 This dissertation aims at empirically demonstrating moderators of the manifestation and chronification of posttraumatic symptoms. The determining factor of PTSD symptom development is commonly assumed to be the mental representation of a traumatic experience. A pathological representation is characterized by an enlarged associative fear structure with very strong interconnections between the included elements. The connections to autobiographical context information are weak. The size or respective number of included elements increases with every recall and thus enhances the probability for future reactivation. These presumptions are included in several recommended therapeutic approaches, but empirical support for the pathological associative (fear) structures is rare.<br />The current dissertation provides insights in strength and accessibility of the pathologically respresented elements and its interconnections among PTSD refugee adolescents.<br />Neurophysiological indicators (MEG) for healthy affective word processing were demonstrated in an enhanced ventral stream activity and sustained late frontal and parietal activity, particularly for pleasant nouns (9 control and PTSD subjects each). The results replicate previous literature with respect to temporal course, current source localization, and preference for pleasant stimuli. Altered affective word processing in PTSD adolescents was evidenced in a strong early occipital response to emotional (particularly unpleasant) words and a subsequent inhibition of cortical activity. The current results correspond with previous findings and are interpreted as an early activation of the associative fear structure element by the emotional arousal and a subsequent cortical avoidance response.<br />Affective word processing was further investigated on the level of response biases in evaluative decisions on affective nouns within a priming design (n = 15 control, n = 10 PTSD; SOA 400 ms). Results revealed several factors that led to a deceleration of evaluative decisions: Response latencies were generally prolonged for PTSD patients and thus suggested a general pathological impairment. In addition, evaluative decisions were decelerated for unpleasant targets among all participants, but this response inhibition was particularly prominent in PTSD participants. PTSD patients response latencies were further decelerated when the target was preceded by a pleasant or neutral prime. Previous literature and the mainly successful replication among PTSD treatment responders and non-responders without migration background suggest a pathologically shifted evaluation of the affective (unpleasant) stimuli: The altered subjective meaning is interpreted as experimental evidence for the extended associative fear structure in PTSD patients. The enhanced associative strength between stimuli with (unpleasant) emotional arousal supports the view of strengthened interconnections within an associative fear structure. The replication trial further revealed that associative fear structures are not influenced by treatment success or treatment type.<br />The dissertation further addressed higher order affective word processing in paired associate learning and related cortical slow wave activity (EEG; N = 19, n = 9 control and n = 10 PTSD subjects). Healthy learning was evidenced in better cued recall performance for pleasant word pairs and repeated list presentation. An early P3 and negative frontal slow wave activity were neurophysiological indicators of healthy associative learning that parallel previous evidence. Altered associative learning in PTSD refugee adolescents was characterized by a particular increase in unpleasant false alarms that suggests difficulties in the discrimination of emotionally arousing (unpleasant) stimuli. These pathological difficulties argue for a general PTSD-specific hypersensitivity for unpleasant arousal and may indicate the reactivation of the associative fear structure. The pathological processing of affective word pairs was supported by an inhibited stimulus evaluation process in (left) frontal regions. A late positive voltage shift in frontal areas further indicated an inhibition of the underlying cortical areas and thus a continuation of the cortical avoidance described above.<br />In conclusion, the current dissertation fills in the discrepancy between the demand for evidence-based therapies and insufficiently investigated presumptions in the therapeutic approaches.

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