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04-05 Neural activity in dissociative and nondissociative PTSD: an fMRI analysis of conscious and nonconscious fear processing

Published online by Cambridge University Press:  24 June 2014

KL Felmingham ,
LM Williams ,
E Falconer ,
AH Kemp ,
P Das ,
A Peduto  and
RA Bryant
KL Felmingham
Affiliation:
The Brain Dynamics Centre, Westmead Millennium Institute, Westmead Hospital and Western Clinical School, University of Sydney, Australia Psychological Medicine, Western Clinical School, University of Sydney; School of Psychology, University of New South Wales
LM Williams
Affiliation:
The Brain Dynamics Centre, Westmead Millennium Institute, Westmead Hospital and Western Clinical School, University of Sydney, Australia Psychological Medicine, Western Clinical School, University of Sydney; School of Psychology, University of New South Wales
E Falconer
Affiliation:
The Brain Dynamics Centre, Westmead Millennium Institute, Westmead Hospital and Western Clinical School, University of Sydney, Australia Neuroscience Institute of Schizophrenia and Allied Disorders (NISAD), New South Wales, Australia
AH Kemp
Affiliation:
The Brain Dynamics Centre, Westmead Millennium Institute, Westmead Hospital and Western Clinical School, University of Sydney, Australia Psychological Medicine, Western Clinical School, University of Sydney; School of Psychology, University of New South Wales
P Das
Affiliation:
The Brain Dynamics Centre, Westmead Millennium Institute, Westmead Hospital and Western Clinical School, University of Sydney, Australia Department of Radiology, Westmead Hospital, Westmead, Australia
A Peduto
Affiliation:
The Brain Dynamics Centre, Westmead Millennium Institute, Westmead Hospital and Western Clinical School, University of Sydney, Australia
RA Bryant
Affiliation:
The Brain Dynamics Centre, Westmead Millennium Institute, Westmead Hospital and Western Clinical School, University of Sydney, Australia Neuroscience Institute of Schizophrenia and Allied Disorders (NISAD), New South Wales, Australia
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Abstract

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Type
Abstracts from ‘Brainwaves’— The Australasian Society for Psychiatric Research Annual Meeting 2006, 6–8 December, Sydney, Australia
Information
Acta Neuropsychiatrica , Volume 18 , Issue 6 , December 2006 , pp. 323 - 324
Copyright
Copyright © 2006 Blackwell Munksgaard

Post-traumatic stress disorder (PTSD) involves variable responses to threat, ranging from hyperreactive to dissociative. While most imaging research has explored hyperreactivity in PTSD, an important but poorly understood subtype of PTSD is dissociation. Recent imaging research suggests that dissociative PTSD is associated with increased medial prefrontal activity in response to threat (Lanius et al. 2002). This accords with neurobiological models that implicate a corticolimbic disconnection in dissociation (Sierra & Berrios 1998). It is critical to explore both the cortical and subcortical networks associated with dissociation during different levels of awareness of fear processing in PTSD. We predicted that whereas conscious processing of fear would be associated with increased mPFC activity, nonconscious processing would bypass inhibitory control and be associated with exaggerated amygdale activity. Twenty-three participants with PTSD, classified as dissociative (n = 12) or nondissociative (n = 11), viewed masked and unmasked fearful and neutral facial expressions. Amygdala and anterior cingulate function was examined with functional magnetic resonance imaging. In line with our predictions, the dissociative PTSD group showed increased ventral anterior cingulate activity to conscious fear faces relative to nondissociative PTSD. In contrast, the dissociative group showed bilateral amygdala activity to masked fear faces compared with nondissociative PTSD. These findings suggest that dissociative PTSD is associated with enhanced automatic amygdala activity under masked conditions and increased regulatory prefrontal processing under controlled processing conditions.