Anika Sierk1, Antje Manthey2, John King3, Chris R Brewin4, James A Bisby5, Henrik Walter2, Neil Burgess5, Judith K Daniels6. 1. Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany; Institute of Cognitive Neuroscience, University College London, London, United Kingdom. 2. Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany. 3. Institute of Cognitive Neuroscience, University College London, London, United Kingdom; Research Department of Clinical, Educational and Health Psychology, University College London, London, United Kingdom. 4. Research Department of Clinical, Educational and Health Psychology, University College London, London, United Kingdom. 5. Institute of Cognitive Neuroscience, University College London, London, United Kingdom; Institute of Neurology, University College London, London, UK. 6. Department of Clinical Psychology, University of Groningen, Groningen, the Netherlands; Psychologische Hochschule Berlin, Germany. Electronic address: J.K.Daniels@rug.nl.
Abstract
BACKGROUND: Posttraumatic stress disorder (PTSD) is characterized by distressing trauma-related memories. According to the dual representation theory, intrusive memories arise from strengthened egocentric encoding and a poor contextual encoding, with spatial context requiring allocentric processing. Contextualization of mental imagery is proposed to be formed hierarchically through the ventral visual stream (VVS) to the hippocampal formation. Here, we tested this notion by investigating whether neuronal aberrations in structures of the VVS or in the hippocampus, as well as allocentric memory performance are associated with intrusive memory severity. METHODS: The sample comprised 33 women with PTSD due to childhood trauma. Allocentric memory performance was measured with the virtual Town Square Task and T1-weighted images acquired on a 3T Siemens Scanner. Intrusive memories were evoked by presenting an audio script describing parts of their trauma (script-driven imagery). RESULTS: Using hierarchical linear regression analysis, we found a significant association between lower intrusive memory severity and higher allocentric spatial memory, controlling for age, working memory, and general visuospatial ability. No significant association was found between cortical thickness of VVS structures, hippocampal volume and intrusive memory severity. Post hoc exploratory analyses revealed a negative correlation between years since index trauma and left hippocampal volume. LIMITATIONS: Our results are based on correlational analyses, causality cannot be inferred. CONCLUSION: This study supports the dual representation theory, which emphasizes the role of allocentric spatial memory for the contextualization of mental imagery in PTSD. Clinical implications are discussed.
BACKGROUND:Posttraumatic stress disorder (PTSD) is characterized by distressing trauma-related memories. According to the dual representation theory, intrusive memories arise from strengthened egocentric encoding and a poor contextual encoding, with spatial context requiring allocentric processing. Contextualization of mental imagery is proposed to be formed hierarchically through the ventral visual stream (VVS) to the hippocampal formation. Here, we tested this notion by investigating whether neuronal aberrations in structures of the VVS or in the hippocampus, as well as allocentric memory performance are associated with intrusive memory severity. METHODS: The sample comprised 33 women with PTSD due to childhood trauma. Allocentric memory performance was measured with the virtual Town Square Task and T1-weighted images acquired on a 3T Siemens Scanner. Intrusive memories were evoked by presenting an audio script describing parts of their trauma (script-driven imagery). RESULTS: Using hierarchical linear regression analysis, we found a significant association between lower intrusive memory severity and higher allocentric spatial memory, controlling for age, working memory, and general visuospatial ability. No significant association was found between cortical thickness of VVS structures, hippocampal volume and intrusive memory severity. Post hoc exploratory analyses revealed a negative correlation between years since index trauma and left hippocampal volume. LIMITATIONS: Our results are based on correlational analyses, causality cannot be inferred. CONCLUSION: This study supports the dual representation theory, which emphasizes the role of allocentric spatial memory for the contextualization of mental imagery in PTSD. Clinical implications are discussed.