neurobiological links between dissociation and emdr marco pagani senior researcher institute of...
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Neurobiological links between dissociation and EMDR
Marco Pagani
Senior Researcher Institute of Cognitive Sciences and Technologies, CNRRome, Italy
Chair of the Neuroimaging Committee of the European Association of Nuclear Medicine
FUNCTIONAL BRAIN
TARGET REGIONS
mPFC modulates emotional response inhibiting amygdala and estinguishing fear response
PREFRONTAL CORTEX
Amygdala is also involved in memory modulation and consolidation
Amygdala has a central role in formation and preservation of emotional memories
AMYGDALA
Lacking inhibitory control from PFC hyperactive amygdala causes excessive firing of cortical and subcortical structures responsible for PTSD symptoms
AMYGDALA
Hippocampus processes episodic and autobiographical memory and is essential in identifying “safe places”
HIPPOCAMPUS
Hippocampus is extremely sensitive to stress and might decrease in volume and neuronal density following chronic cortisol secretion
HIPPOCAMPUS
ANTERIOR AND POSTERIOR CINGULATE CORTEX
ANTERIOR CINGULATE CORTEX
With amygdala and insula modulates mood and anxiety
The tight connections with hippocampus contribute to memory formation
Connectivity with frontal cortex is related to self-esteem and self-evaluation
Anterior cingulate cohordinates hunger and sleep
Posterior cingulate processes the “self” and conscious experiences of emotions and feelings
POSTERIOR CINGULATE CORTEX
With precuneus it is involved in coping with physical threats and processing stressing material
Is relevant in enhancing attention to internal representation of memories of similar experiences
Magnetic resonance exploits magnetic fields to produce anatomical images
It is widespread and relatively cheap
MAGNETIC RESONANCE
STRUCTURAL MAGNETIC RESONANCE
fMRI measures the altered levels of cerebral blood oxygenation. Regional neural activity results in increased local CBF producing an increase in oxyhemoglobin
This leads to a net decrease in de-oxyhaemoglobin and the relative change in concentrations of the two results in a change in signal intensity
Neuronal activity
Blood oxygen level-dependent (BOLD) contrast
fMRI
FUNCTIONAL MAGNETIC RESONANCE
Injected radioisotopes distribute in the brain proportionally to the function to be investigated (blood flow, metabolism or receptor density)
SPECT and PET
EEG
NEUROIMMAGING IN EEG
POST-TRAUMATIC STRESS DISORDER
In DSM-5 PTSD is defined by the coexistence of 4 clusters of symptoms
re-experiencing (intrusive thoughts, flashbacks, nightmares)
avoidance (memory impairment, feelings of detachment, efforts to avoid thoughts, places or people associated with the trauma, social withdrawal)
hyperarousal (abnormal startle responses, hypervigilance, irritability, sleep disturbance, difficulty concentrating)
negative alterations (mood and cognition)
The first neuroimaging studies on PTSD were performed in the USA at military hospitals including mostly Vietnam war veterans
PTSD AND NEUROIMAGING
PTSD AND NEUROIMAGING
STATISTICAL ANALYSES
t-statistics
PCA/ICANetworking
UNIVARIATE
MULTIVARIATE
CONNECTIVITY IN CIVILIAN TRAUMAS
Functional connectivity
Amygdala has strong connections with anterior cingulate, insula and hippocampus
Bremner et al. Current Psychiatry Reports 2002, 4:254–263
Gilboa et al. Biol Psych 2004; 55:263–272
PTSD AND NEUROIMAGING
All neuroimaging studies converge in identifying as implicated in PTSD:
• prefrontal cortex (PFC)• amygdala• hippocampus• insula• Anterior and posterior cingulate cortex
The impairment of PFC associated with a hyper-reactivity of the amygdala constitutes the core neural correlate of PTSD
PTSD AND NEUROIMAGING
NEUROIMAGING and PSYCHOTHERAPY
Neuroimaging techniques have been used in an attempt to shed light on the neurobiological correlates of various psychotherapies revealing their neurobiological effects
Despite positive clinical outcomes functional and neuroanatomical studies are still poorly randomized and insufficient to draw robust conclusions
Peres et al. 2011 – J Psychiatry Research 45:727-734
NEUROIMAGING and PSYCHOTHERAPYETCR - fMRI
NEUROIMAGING and PSYCHOTHERAPYMINDFULNESS
NEUROIMAGING and PSYCHOTHERAPY
EMDR AND SPECT
Bryant et al. 2008; Psychological Medicine 38:555-561
NEUROIMAGING and PSYCHOTHERAPYCBT - fMRI
PTSDNS>S
EMDRR>NR
EMDR AND MRI
Functional and anatomical studies support the evidence of neurobiological models explaining the changes which take place following PTSD-related psychotherapies
These findings call for continued commitment to unravelling the pathophysiological mechanisms underlying these effective treatments of PTSD
NEUROIMAGING and PSYCHOTHERAPY
5 MINUTES FOR QUESTIONS
TIME TO METABOLIZE
AND STRETCHING
Both treatment are effective but EMDR results in a faster disappearance of symptoms
WHY EMDR?
EMDR AND BET
To explore the technical feasibility of the on-line recording of whole EMDR sessions by means of EEG and data analyses
To identify the regions activated during the bilateral ocular stimulation upon traumatic memory exposure
EMDR AND EEG
CLIENTS PRE-EMDR vs non-symptomatic CONTROLS DURING BILATERAL OCULAR STIMULATION
CLIENTS PRE-EMDR vs CLIENTS POST-EMDR NEUROPSYCHOLOGICAL DATA
CLIENTS PRE-EMDR vs CLIENTS POST-EMDR DURING BILATERAL OCULAR STIMULATION
EMDR AND EEG
We monitored by EEG EMDR psychotherapy sessions in two groups of clients
EMDR AND EEG
In the symptomatic phase trauma exposure caused prevalent prefrontal activation
After symptoms disappearance the activation shifted to cognitive associative areas
In chronically exposed clients the neurobiological response was similar to that in healthy controls
The social context impacts on the neurobiological response to trauma exposure
MEMORY MECHANISMS
NEUROIMAGING AND DISSOCIATION
Prefrontal and limbic structures underlie dissociative responses in PTSD.
Differences observed clinically, psychophysiologically, and neurobiologically between patients with dissociative versus non-dissociative responses may suggest different neuronal mechanisms underlying these two distinct reactions.
NEUROIMAGING AND DISSOCIATION
Dissociation is a regulatory strategy invoked to cope with extreme arousal in PTSD, but this strategy appears to function only during conscious processing of threat
Conscious fear Unconscious fear
NEUROIMAGING AND DISSOCIATION
Dissociation correlated positively with activity in the left medial prefrontal and right superior temporal cortices, and negatively with the left superior temporal cortex
NEUROIMAGING AND DISSOCIATION
Dissociative subjects show significant dissociative response including depersonalization and derealization
PTSD AND DISSOCIATION
Dissociative symptoms often occur together with Post-Traumatic Stress Disorder (PTSD)
The role that dissociation plays in the genesis of PTSD and its current taxonomy as an anxiety disorder separate from dissociative disorders has been put into question
Neuroimaging studies have shown a rather heterogeneous pattern of results, by which dissociation might be associated with functional alterations in various areas
Some works have suggested that PTSD subjects can be divided into two subtypes:
subjects who relive their traumatic experiences in form of intensely upsetting recollections and flashbacks, accompanied by an increase in heart rate (hyperarousal subtype, characterized by so-called ‘primary dissociation’)
PTSD AND DISSOCIATION
subjects who show dissociative responses and report experiences such as depersonalization, derealization or ‘zooming out’ phenomena, and do not show any increase in heart rate (dissociative subtype, characterized by so-called ‘secondary dissociation’)
PTSD AND DISSOCIATION
AIMS
The aims of this study were:
to investigate brain structural alteration associated with the presence of dissociative traits along a continuum in a group of traumatized subjects with or without PTSD
to explore the neural correlates associated with different psychological dimensions of dissociation
PTSD AND DISSOCIATION
Thirty-two subjects either developing (N=15) or non-developing (N=17) PTSD underwent MRI and Gray matter volume (GMV) was analyzed
Trait Dissociative Experience Scale (DES), subscales for pathological (DES-T) and non-pathological (DES-A) dissociation, and other clinical measures were assessed
METHODS
PTSD and non-PTSD subjects were compared to evaluate brain alterations related to PTSD pathology
Correlation analyses between dissociation measures and GMV were performed on the whole sample (N=32), irrespective of PTSD diagnosis, to identify alterations related to trait dissociation
PTSD AND DISSOCIATION
RESULTS
Regions in which grey matter volume correlated inversely with PTSD symptoms (in red) and positively (in blue) with overall trait dissociation score
PTSD AND DISSOCIATION
Such increase was mainly due to non-PTSD subjects (green diamonds) in which GMV was strongly positively correlated to trait Dissociation scores
RESULTS
PTSD AND DISSOCIATION
RESULTS
Correlations between GMV and trait, pathological and non-pathological dissociation
PTSD AND DISSOCIATION
Our results indicate that PTSD and trait dissociation are associated with opposite patterns of GMV alterations in medial and lateral prefrontal cortex, where PTSD is associated with a volumetric decrease, while trait dissociation with a volumetric increase.
CONCLUSIONS
The peculiar increase in GMV in lateral PFC in non pathological dissociation might be associated with an enhanced working memory capacities and unconscious suppression of unwanted memories
PTSD AND DISSOCIATION
We have also shown that in sub-clinically dissociated subjects, the tendency to experience pathological dissociative phenomena (i.e., pathological dissociation) and absorption or imaginative involvement (i.e., non-pathological dissociation) widely share the same neural substrates supporting a view of dissociation along a continuum.
CONCLUSIONS
Our results are consistent with previous findings and might underlie the different patterns of emotional modulation (under- vs. overmodulation) and cognitive style (i.e., self-related processing, episodic/autobiographical memory, attention, and working memory) observed in PTSD and dissociation.
We are not claiming that we have solid evidence for all of the links and interpretations in the train of logic presented here
Stickgold, Journal of Clinical Psychology 2002; 58: 61-75
MECHANISM OF ACTIONINTEGRATION OF MEMORIES (Stickgold 2002)
Our goal is to demonstrate that there is a reasonable explanation of our findings which is consonant with modern neurobiology and cognitive neuroscience
THANKSmarco.pagani@istc.cnr.it
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