Browsing by Author "Dolcos, Florin"

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    Brain activity during episodic retrieval of autobiographical and laboratory events: an fMRI study using a novel photo paradigm.
    (J Cogn Neurosci, 2004-11) Cabeza, Roberto; Prince, Steve E; Daselaar, Sander M; Greenberg, Daniel L; Budde, Matthew; Dolcos, Florin; LaBar, Kevin S; Rubin, David C
    Functional neuroimaging studies of episodic memory retrieval generally measure brain activity while participants remember items encountered in the laboratory ("controlled laboratory condition") or events from their own life ("open autobiographical condition"). Differences in activation between these conditions may reflect differences in retrieval processes, memory remoteness, emotional content, retrieval success, self-referential processing, visual/spatial memory, and recollection. To clarify the nature of these differences, a functional MRI study was conducted using a novel "photo paradigm," which allows greater control over the autobiographical condition, including a measure of retrieval accuracy. Undergraduate students took photos in specified campus locations ("controlled autobiographical condition"), viewed in the laboratory similar photos taken by other participants (controlled laboratory condition), and were then scanned while recognizing the two kinds of photos. Both conditions activated a common episodic memory network that included medial temporal and prefrontal regions. Compared with the controlled laboratory condition, the controlled autobiographical condition elicited greater activity in regions associated with self-referential processing (medial prefrontal cortex), visual/spatial memory (visual and parahippocampal regions), and recollection (hippocampus). The photo paradigm provides a way of investigating the functional neuroanatomy of real-life episodic memory under rigorous experimental control.
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    Neural correlates of emotional processing in depression: changes with cognitive behavioral therapy and predictors of treatment response.
    (J Psychiatr Res, 2011-05) Ritchey, Maureen; Dolcos, Florin; Eddington, Kari M; Strauman, Timothy J; Cabeza, Roberto
    Major depressive disorder (MDD) is characterized by the presence of disturbances in emotional processing. However, the neural correlates of these alterations, and how they may be affected by therapeutic interventions, remain unclear. The present study addressed these issues in a preliminary investigation using functional magnetic resonance imaging (fMRI) to examine neural responses to positive, negative, and neutral pictures in unmedicated MDD patients (N = 22) versus controls (N = 14). After this initial scan, MDD patients were treated with cognitive behavioral therapy (CBT) and scanned again after treatment. Within regions that showed pre-treatment differences between patients and controls, we tested the association between pre-treatment activity and subsequent treatment response as well as activity changes from pre- to post-treatment. This study yielded three main findings. First, prior to treatment and relative to controls, patients exhibited overall reduced activity in the ventromedial prefrontal cortex (PFC), diminished discrimination between emotional and neutral items in the amygdala, caudate, and hippocampus, and enhanced responses to negative versus positive stimuli in the left anterior temporal lobe (ATL) and right dorsolateral PFC. Second, CBT-related symptom improvement in MDD patients was predicted by increased activity at baseline in ventromedial PFC as well as the valence effects in the ATL and dorsolateral PFC. Third, from pre- to post-treatment, MDD patients exhibited overall increases in ventromedial PFC activation, enhanced arousal responses in the amygdala, caudate, and hippocampus, and a reversal of valence effects in the ATL. The study was limited by the relatively small sample that was able to complete both scan sessions, as well as an inability to determine the influence of comorbid disorders within the current sample. Nevertheless, components of the neural networks corresponding to emotion processing disturbances in MDD appear to resolve following treatment and are predictive of treatment response, possibly reflecting improvements in emotion regulation processes in response to CBT.
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    Neurobehavioral Mechanisms of Resilience Against Emotional Distress: An Integrative Brain-Personality-Symptom Approach Using Structural Equation Modeling.
    (Personality neuroscience, 2018-01) Moore, Matthew; Culpepper, Steven; Phan, K Luan; Strauman, Timothy J; Dolcos, Florin; Dolcos, Sanda
    Clarifying individual differences that predict resilience or vulnerability to emotional distress is crucial for identifying etiological factors contributing to affective disturbances, and to promoting emotional well-being. Despite recent progress identifying specific brain regions and personality traits, it remains unclear whether there are common factors underlying the structural aspects of the brain and the personality traits that, in turn, protect against symptoms of emotional distress. In the present study, an integrative structural equation model was developed to examine the associations among (1) a latent construct of Control, representing the volumes of a system of prefrontal cortical (PFC) regions including middle, inferior, and orbital frontal cortices; (2) a latent construct of Resilience personality traits including cognitive reappraisal, positive affectivity, and optimism; and (3) Anxiety and Depression symptoms, in a sample of 85 healthy young adults. Results showed that the latent construct of PFC volumes positively predicted the latent construct of Resilience, which in turn negatively predicted Anxiety. Mediation analysis confirmed that greater latent PFC volume is indirectly associated with lower Anxiety symptoms through greater latent trait Resilience. The model did not show a significant mediation for Depression. These results support the idea that there are common volumetric and personality factors that help protect against symptoms of emotional distress. These findings provide strong evidence that such brain-personality-symptom approaches can provide novel insights with valuable implications for understanding the interaction of these factors in healthy and clinically diagnosed individuals.
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    Reduced hippocampal and amygdala activity predicts memory distortions for trauma reminders in combat-related PTSD.
    (J Psychiatr Res, 2011-05) Hayes, Jasmeet Pannu; LaBar, Kevin S; McCarthy, Gregory; Selgrade, Elizabeth; Nasser, Jessica; Dolcos, Florin; VISN 6 Mid-Atlantic MIRECC workgroup; Morey, Rajendra A
    Neurobiological models of posttraumatic stress disorder (PTSD) suggest that altered activity in the medial temporal lobes (MTL) during encoding of traumatic memories contribute to the development and maintenance of the disorder. However, there is little direct evidence in the PTSD literature to support these models. The goal of the present study was to examine MTL activity during trauma encoding in combat veterans using the subsequent memory paradigm. Fifteen combat veterans diagnosed with PTSD and 14 trauma-exposed control participants viewed trauma-related and neutral pictures while undergoing event-related fMRI. Participants returned one week after scanning for a recognition memory test. Region-of-interest (ROI) and voxel-wise whole brain analyses were conducted to examine the neural correlates of successful memory encoding. Patients with PTSD showed greater false alarm rates for novel lures than the trauma-exposed control group, suggesting reliance on gist-based representations in lieu of encoding contextual details. Imaging analyses revealed reduced activity in the amygdala and hippocampus in PTSD patients during successful encoding of trauma-related stimuli. Reduction in left hippocampal activity was associated with high arousal symptoms on the Clinician-Administered PTSD Scale (CAPS). The behavioral false alarm rate for traumatic stimuli co-varied with activity in the bilateral precuneus. These results support neurobiological theories positing reduced hippocampal activity under conditions of high stress and arousal. Reduction in MTL activity for successfully encoded stimuli and increased precuneus activity may underlie reduced stimulus-specific encoding and greater gist memory in patients with PTSD, leading to maintenance of the disorder.
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    Serotonin transporter gene polymorphisms and brain function during emotional distraction from cognitive processing in posttraumatic stress disorder.
    (BMC Psychiatry, 2011-05-05) Morey, Rajendra A; Hariri, Ahmad R; Gold, Andrea L; Hauser, Michael A; Munger, Heidi J; Dolcos, Florin; McCarthy, Gregory
    BACKGROUND: Serotonergic system dysfunction has been implicated in posttraumatic stress disorder (PTSD). Genetic polymorphisms associated with serotonin signaling may predict differences in brain circuitry involved in emotion processing and deficits associated with PTSD. In healthy individuals, common functional polymorphisms in the serotonin transporter gene (SLC6A4) have been shown to modulate amygdala and prefrontal cortex (PFC) activity in response to salient emotional stimuli. Similar patterns of differential neural responses to emotional stimuli have been demonstrated in PTSD but genetic factors influencing these activations have yet to be examined. METHODS: We investigated whether SLC6A4 promoter polymorphisms (5-HTTLPR, rs25531) and several downstream single nucleotide polymorphisms (SNPs) modulated activity of brain regions involved in the cognitive control of emotion in post-9/11 veterans with PTSD. We used functional MRI to examine neural activity in a PTSD group (n = 22) and a trauma-exposed control group (n = 20) in response to trauma-related images presented as task-irrelevant distractors during the active maintenance period of a delayed-response working memory task. Regions of interest were derived by contrasting activation for the most distracting and least distracting conditions across participants. RESULTS: In patients with PTSD, when compared to trauma-exposed controls, rs16965628 (associated with serotonin transporter gene expression) modulated task-related ventrolateral PFC activation and 5-HTTLPR tended to modulate left amygdala activation. Subsequent to combat-related trauma, these SLC6A4 polymorphisms may bias serotonin signaling and the neural circuitry mediating cognitive control of emotion in patients with PTSD. CONCLUSIONS: The SLC6A4 SNP rs16965628 and 5-HTTLPR are associated with a bias in neural responses to traumatic reminders and cognitive control of emotions in patients with PTSD. Functional MRI may help identify intermediate phenotypes and dimensions of PTSD that clarify the functional link between genes and disease phenotype, and also highlight features of PTSD that show more proximal influence of susceptibility genes compared to current clinical categorizations.
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    The impact of anxiety-inducing distraction on cognitive performance: a combined brain imaging and personality investigation.
    (PLoS One, 2010-11-30) Denkova, Ekaterina; Wong, Gloria; Dolcos, Sanda; Sung, Keen; Wang, Lihong; Coupland, Nicholas; Dolcos, Florin
    BACKGROUND: Previous investigations revealed that the impact of task-irrelevant emotional distraction on ongoing goal-oriented cognitive processing is linked to opposite patterns of activation in emotional and perceptual vs. cognitive control/executive brain regions. However, little is known about the role of individual variations in these responses. The present study investigated the effect of trait anxiety on the neural responses mediating the impact of transient anxiety-inducing task-irrelevant distraction on cognitive performance, and on the neural correlates of coping with such distraction. We investigated whether activity in the brain regions sensitive to emotional distraction would show dissociable patterns of co-variation with measures indexing individual variations in trait anxiety and cognitive performance. METHODOLOGY/PRINCIPAL FINDINGS: Event-related fMRI data, recorded while healthy female participants performed a delayed-response working memory (WM) task with distraction, were investigated in conjunction with behavioural measures that assessed individual variations in both trait anxiety and WM performance. Consistent with increased sensitivity to emotional cues in high anxiety, specific perceptual areas (fusiform gyrus--FG) exhibited increased activity that was positively correlated with trait anxiety and negatively correlated with WM performance, whereas specific executive regions (right lateral prefrontal cortex--PFC) exhibited decreased activity that was negatively correlated with trait anxiety. The study also identified a role of the medial and left lateral PFC in coping with distraction, as opposed to reflecting a detrimental impact of emotional distraction. CONCLUSIONS: These findings provide initial evidence concerning the neural mechanisms sensitive to individual variations in trait anxiety and WM performance, which dissociate the detrimental impact of emotion distraction and the engagement of mechanisms to cope with distracting emotions. Our study sheds light on the neural correlates of emotion-cognition interactions in normal behaviour, which has implications for understanding factors that may influence susceptibility to affective disorders, in general, and to anxiety disorders, in particular.