Margaret A. Carson

Bio: Margaret A. Carson is an academic researcher from Saint Anselm College. The author has contributed to research in topics: Anterior cingulate cortex & Prefrontal cortex. The author has an hindex of 9, co-authored 10 publications receiving 1417 citations. Previous affiliations of Margaret A. Carson include Veterans Health Administration.

Regional Cerebral Blood Flow in the Amygdala and Medial Prefrontal Cortex During Traumatic Imagery in Male and Female Vietnam Veterans With PTSD

Abstract: Context: Theoretical neuroanatomic models of posttraumatic stress disorder (PTSD) and the results of previous neuroimaging studies of PTSD highlight the potential importance of the amygdala and medial prefrontal regions in this disorder. However, the functional relationship between these brain regions in PTSD has not been directly examined. Objective: To examine the relationship between the amygdala and medial prefrontal regions during symptom provocation in male combat veterans (MCVs) and female nurse veterans (FNVs) with PTSD. Design: Case-control study. Setting: Academic medical center. Participants: Volunteer sample of 17 (7 men and 10 women) Vietnam veterans with PTSD (PTSD group) and 19 (9 men and 10 women) Vietnam veterans without PTSD (control group). Main Outcome Measures: We used positron emission tomography and the script-driven imagery paradigm to study regional cerebral blood flow (rCBF) during the recollection of personal traumatic and neutral events. Psychophysiologic and emotional self-report data also were obtained to confirm the intended effects of script-driven imagery. Results: The PTSD group exhibited rCBF decreases in medial frontal gyrus in the traumatic vs neutral comparison. When this comparison was conducted separately by subgroup, MCVs and FNVs with PTSD exhibited these medial frontal gyrus decreases. Only MCVs exhibited rCBF increases in the left amygdala. However, for both subgroups with PTSD, rCBF changes in medial frontal gyrus were inversely correlated with rCBF changes in the left amygdala and the right amygdala/ periamygdaloid cortex. Furthermore, in the traumatic condition, for both subgroups with PTSD, symptom severity was positively related to rCBF in the right amygdala and negatively related to rCBF in medial frontal gyrus. Conclusions: These results suggest a reciprocal relationship between medial prefrontal cortex and amygdala function in PTSD and opposing associations between activity in these regions and symptom severity consistent with current functional neuroanatomic models of this disorder. Arch Gen Psychiatry. 2004;61:168-176

Selectively reduced regional cortical volumes in post-traumatic stress disorder.

Abstract: Different subterritories of anterior cingulate cortex (ACC) and adjacent ventromedial frontal cortex have been shown to serve distinct functions. This scheme has influenced contemporary pathophysiologic models of psychiatric disorders. Prevailing neurocircuitry models of post-traumatic stress disorder (PTSD) implicate dysfunction within pregenual ACC and subcallosal cortex (SC), as well as amygdala and hippocampus. In the current study, cortical parcellation of magnetic resonance imaging data was performed to test for volumetric differences in pregenual ACC and SC, between women with PTSD and trauma-exposed women without PTSD. The PTSD group exhibited selectively decreased pregenual ACC and SC volumes. These results are consistent with contemporary schemes regarding functional and structural dissection of frontal cortex, and suggest specific regional cortical pathology in PTSD.

PTSD Arousal and Depression Symptoms Associated With Increased Right-Sided Parietal EEG Asymmetry.

Abstract: Researchers have proposed that depression and particular types of anxiety are associated with unique patterns of regional brain activation. The authors examined the relationship among posttraumatic stress disorder (PTSD), anxiety, and depressive symptoms and frontal, temporal, and parietal EEG alpha asymmetry in female Vietnam War nurse veterans. The results indicate that PTSD arousal symptoms are associated with increased right-sided parietal activation. However, the combination of arousal, depression, and their interaction explain more than twice the variance in parietal asymmetry compared with arousal alone. The results support the contention that the association between anxiety and right-sided posterior activation is specific to the anxious arousal subtype. These findings underscore the importance of isolating, both theoretically and statistically, emotional subcomponents in studies of regional brain activation.

Psychophysiologic assessment of posttraumatic stress disorder in Vietnam nurse veterans who witnessed injury or death.

Abstract: This study examined whether witnessing death and injury could produce psychophysiologically responsive posttraumatic stress disorder (PTSD). Participants consisted of medication-free female Vietnam nurse veterans with a diagnosis of current PTSD (n = 17) and who never had PTSD (n = 21), related to their military service. Individualized scripts describing personal traumatic military nursing events, a standard military nursing event, and other life events were tape recorded and played back to the participant while heart rate, skin conductance, and facial electromyograms were recorded. Nurses with PTSD showed significantly larger physiologic responses than non-PTSD nurses only during imagery of military-related nursing events. The groups' self-reported emotional responses did not differ during imagery. Psychophysiologic results support the proposition that witnessing death and serious injury to others is sufficiently stressful to cause PTSD.

Decreased regional cerebral blood flow in medial prefrontal cortex during trauma-unrelated stressful imagery in Vietnam veterans with post-traumatic stress disorder.

Abstract: BackgroundNeuroimaging research has demonstrated medial prefrontal cortex (mPFC) hyporesponsivity and amygdala hyperresponsivity to trauma-related or emotional stimuli in post-traumatic stress disorder (PTSD). Relatively few studies have examined brain responses to the recollection of stressful, but trauma-unrelated, personal events in PTSD. In the current study, we sought to determine whether regional cerebral blood flow (rCBF) abnormalities in mPFC and amygdala in PTSD could be observed during the recollection of trauma-unrelated stressful personal events.MethodParticipants were 35 right-handed male combat veterans (MCVs) and female nurse veterans (FNVs) who served in Vietnam: 17 (seven male, 10 female) with current military-related PTSD and 18 (nine male, nine female) with no current or lifetime PTSD. We used positron emission tomography (PET) and script-driven imagery to study rCBF during the recollection of trauma-unrelated stressful versus neutral and traumatic events.ResultsVoxelwise tests revealed significant between-group differences for the trauma-unrelated stressful versus neutral comparison in mPFC, specifically in the anterior cingulate cortex (ACC). Functional region of interest (ROI) analyses demonstrated that this interaction in mPFC represented greater rCBF decreases in the PTSD group during trauma-unrelated stressful imagery relative to neutral imagery compared to the non-PTSD group. No differential amygdala activation was observed between groups or in either group separately.ConclusionsVeterans with PTSD, compared to those without PTSD, exhibited decreased rCBF in mPFC during mental imagery of trauma-unrelated stressful personal experiences. Functional neuroanatomical models of PTSD must account for diminished mPFC responses that extend to emotional stimuli, including stressful personal experiences that are not directly related to PTSD.

Functional Neuroimaging of Anxiety: A Meta-Analysis of Emotional Processing in PTSD, Social Anxiety Disorder, and Specific Phobia

Abstract: Objective: The study of human anxiety disorders has benefited greatly from functional neuroimaging approaches. Individual studies, however, vary greatly in their findings. The authors searched for common and disorder-specific functional neurobiological deficits in several anxiety disorders. The authors also compared these deficits to the neural systems engaged during anticipatory anxiety in healthy subjects. Method: Functional magnetic resonance imaging and positron emission tomography studies of posttraumatic stress disorder (PTSD), social anxiety disorder, specific phobia, and fear conditioning in healthy individuals were compared by quantitative meta-analysis. Included studies compared negative emotional processing to baseline, neutral, or positive emotion conditions. Results: Patients with any of the three disorders consistently showed greater activity than matched comparison subjects in the amygdala and insula, structures linked to negative emotional responses. A similar pattern was observed during f...

The Adolescent Brain

Abstract: Adolescence is a developmental period characterized by suboptimal decisions and actions that are associated with an increased incidence of unintentional injuries, violence, substance abuse, unintended pregnancy, and sexually transmitted diseases. Traditional neurobiological and cognitive explanations for adolescent behavior have failed to account for the nonlinear changes in behavior observed during adolescence, relative to both childhood and adulthood. This review provides a biologically plausible model of the neural mechanisms underlying these nonlinear changes in behavior. We provide evidence from recent human brain imaging and animal studies that there is a heightened responsiveness to incentives and socioemotional contexts during this time, when impulse control is still relatively immature. These findings suggest differential development of bottom-up limbic systems, implicated in incentive and emotional processing, to top-down control systems during adolescence as compared to childhood and adulthood. This developmental pattern may be exacerbated in those adolescents prone to emotional reactivity, increasing the likelihood of poor outcomes.

Uncertainty and anticipation in anxiety: an integrated neurobiological and psychological perspective.

Abstract: Uncertainty about a possible future threat disrupts our ability to avoid it or to mitigate its negative impact and thus results in anxiety. Here, we focus the broad literature on the neurobiology of anxiety through the lens of uncertainty. We identify five processes that are essential for adaptive anticipatory responses to future threat uncertainty and propose that alterations in the neural instantiation of these processes result in maladaptive responses to uncertainty in pathological anxiety. This framework has the potential to advance the classification, diagnosis and treatment of clinical anxiety.