Functional and Structural Connectivity Between the Perigenual Anterior Cingulate and Amygdala in Bipolar Disorder (original) (raw)
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Molecular Psychiatry, 2007
Bipolar disorder has been associated with anatomical as well as functional abnormalities in a brain network that mediates normal and impaired emotion regulation. Previous brain imaging studies have highlighted the subgenual cingulate (SC) and the amygdalo-hippocampal (AH) complex as core regions of this network. Thus we investigated white matter (WM) fiber tracts between the SC and the AH region, the uncinate fasciculus, as well as between two control regions (pons and cerebellum), using diffusion tensor imaging tractography in 16 euthymic bipolar patients (BP) and 16 sex-, age-and handedness-matched controls. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) of the reconstructed fiber bundle and the number of virtual reconstructed fibers were compared between groups. The tractography results revealed a significantly increased number of reconstructed fibers between the left SC and left AH in BP as compared to healthy controls. FA and ADC of the reconstructed fiber tract did not differ significantly between the groups. Furthermore, no significant group differences were observed neither for reconstructed fiber tracts between the right SC and right AH nor between the control regions. The present results suggest an altered WM pathway between the left SC and AH region and thus extend previous findings of anatomical and functional modifications in these structures in BP.
Harvard Review of Psychiatry, 2019
Frequently implicated in psychotic spectrum disorders, the amygdala serves as an important hub for elucidating the convergent and divergent neural substrates in schizophrenia and bipolar disorder, the two most studied groups of psychotic spectrum conditions. A systematic search of electronic databases through December 2017 was conducted to identify neuroimaging studies of the amygdala in schizophrenia and bipolar disorder, focusing on structural MRI, diffusion tensor imaging (DTI), and resting-state functional connectivity studies, with an emphasis on cross-diagnostic studies. Ninety-four independent studies were selected for the present review (49 structural MRI, 27 DTI, and 18 resting-state functional MRI studies). Also selected, and analyzed in a separate meta-analysis, were 33 volumetric studies with the amygdala as the region-of-interest. Reduced left, right, and total amygdala volumes were found in schizophrenia, relative to both healthy controls and bipolar subjects, even when restricted to cohorts in the early stages of illness. No volume abnormalities were observed in bipolar subjects relative to healthy controls. Shape morphometry studies showed either amygdala deformity or no differences in schizophrenia, and no abnormalities in bipolar disorder. In contrast to the volumetric findings, DTI studies of the uncinate fasciculus tract (connecting the amygdala with the medial-and orbitofrontal cortices) largely showed reduced fractional anisotropy (a marker of white matter microstructure abnormality) in both schizophrenia and bipolar patients, with no cross-diagnostic differences. While decreased amygdalar-orbitofrontal functional connectivity was generally observed in schizophrenia, varying patterns of amygdalar-orbitofrontal connectivity in bipolar disorder were found. Future studies can consider adopting longitudinal approaches with multimodal imaging and more extensive clinical subtyping to probe amygdalar subregional changes and their relationship to the sequelae of psychotic disorders.
Bipolar Disorders, 2012
Objective-Bipolar I disorder is characterized by affective symptoms varying between depression and mania. The specific neurophysiology responsible for depression in bipolar I disorder is unknown, but prior neuroimaging studies suggest impairments in corticolimbic regions that are responsible for regulating emotion. The amygdala seems to play a central role in this network and is responsible for appraisal of emotional stimuli. To further understand the role of the amygdala in the generation of mood symptoms, we used functional magnetic resonance imaging (fMRI) to examine a group of patients with bipolar I disorder longitudinally.
Frontal-Amygdala Connectivity Alterations During Emotion Downregulation in Bipolar I Disorder
Biological Psychiatry, 2013
Background-The symptoms of bipolar disorder suggest dysfunction of emotion regulatory networks. In healthy control populations, down-regulation of emotional responses activates the ventral lateral prefrontal cortex (vlPFC) and dampens amygdala activation. This study investigated frontal and limbic function and connectivity during emotion down-regulation in euthymic subjects with bipolar I disorder (BPI) and healthy control subjects. Methods-30 BPI and 26 control subjects underwent fMRI scanning while performing an emotion processing task with passive viewing and emotion down-regulation conditions. Contrasts were made for each group comparing the down-regulation and passive viewing conditions and these were entered into a between-group random effects analysis to assess group differences in activation. Psychophysiological Interaction (PPI) analyses were conducted to test for significant group differences in functional connectivity between the amygdala and inhibitory frontal regions (i.e., vlPFC). Results-Control subjects showed the expected robust bilateral activation of frontal and limbic regions during passive viewing and emotion down-regulation tasks. Between-group analyses revealed similar activation of BP and control subjects during passive viewing but significantly decreased activation in bilateral vlPFC, bilateral anterior and posterior cingulate, medial frontal gyrus and bilateral dlPFC during emotion down-regulation in subjects with BP. Connectivity
The American Journal of Psychiatry, 2012
OBJECTIVE: Although the amygdala and ventrolateral prefrontal cortex have been implicated in the pathophysiology of bipolar I disorder, the neural mechanisms underlying bipolar II disorder remain unknown. The authors examined neural activity in response to negative emotional faces during an emotion perception task that reliably activates emotion regulatory regions. METHOD: Twenty-one nonmedicated depressed bipolar II patients and 21 healthy comparison subjects underwent functional MRI (fMRI) while performing an emotional face-matching task. Within- and between-group whole-brain fMRI activation and seed-based connectivity analyses were conducted. RESULTS: In depressed bipolar II patients, random-effects between-group fMRI analyses revealed a significant reduction in activation in several regions, including the left and right ventrolateral prefrontal cortices (Brodmann's area [BA] 47) and the right amygdala, a priori regions of interest. Additionally, bipolar patients exhibited significantly reduced negative functional connectivity between the right amygdala and the right orbitofrontal cortex (BA 10) as well as the right dorsolateral prefrontal cortex (BA 46) relative to healthy comparison subjects. CONCLUSIONS: These findings suggest that bipolar II depression is characterized by reduced regional orbitofrontal and limbic activation and altered connectivity in a fronto-temporal circuit implicated in working memory and emotional learning. While the amygdala hypoactivation observed in bipolar II depression is opposite to the direction seen in bipolar I mania and may therefore be state dependent, the observed orbitofrontal cortex hypoactivation is consistent with findings in bipolar I depression, mania, and euthymia, suggesting a physiologic trait marker of the disorder. Comment in The highs and lows of amygdala reactivity in bipolar disorders. [Am J Psychiatry. 2012]""
Journal of Child Psychology and Psychiatry, 2008
Background-Pediatric bipolar disorder (BD), a highly debilitating illness, is characterized by amygdala abnormalities, i.e., volume reduction and hyperactivation during face processing. Evidence of perturbed amygdala functional connectivity with other brain regions would implicate a distributed neural circuit in the pathophysiology of BD, and would further elucidate the neural mechanisms associated with BD face emotion misinterpretation.
Psychiatry Research: …, 2010
Trait abnormalities in bipolar disorder (BD) within ventral prefrontal cortex (vPFC) and amygdala suggest dysfunction in their connectivity. This study employed low frequency resting state functional magnetic resonance imaging (LFRS-fMRI) to analyze functional connectivity between ventral prefrontal cortex (vPFC) and amygdala in BD. LFRS-fMRI identified a negative correlation in vPFC-amygdala activity, and the magnitude of this correlation was greater in healthy participants than in subjects with BD. Additionally, whole brain analysis revealed higher correlations between left and right vPFC in BD, as well as with ventral striatum.
Schizophrenia Bulletin
Bipolar illness is a debilitating neuropsychiatric disorder associated with alterations in the ventral anterior cingulate cortex (vACC), a brain region thought to regulate emotional behavior. Although recent data-driven functional connectivity studies provide evidence consistent with this possibility, the role of vACC in bipolar illness and its pattern of whole brain connectivity remain unknown. Furthermore, no study has established whether vACC exhibits differential whole brain connectivity in bipolar patients with and without cooccurring psychosis and whether this pattern resembles that found in schizophrenia. We conducted a human resting-state functional connectivity investigation focused on the vACC seed in 73 remitted bipolar I disorder patients (33 with psychosis history), 56 demographically matched healthy comparison subjects, and 73 demographically matched patients with chronic schizophrenia. Psychosis history within the bipolar disorder group corresponded with significant between-group connectivity alterations along the dorsal medial prefrontal surface when using the vACC seed. Patients with psychosis history showed reduced connectivity (Cohen's d = −0.69), whereas those without psychosis history showed increased vACC coupling (Cohen's d = 0.8) relative to controls. The vACC connectivity observed in chronic schizophrenia patients was not significantly different from that seen in bipolar patients with psychosis history but was significantly reduced compared with that in bipolar patients without psychosis history. These robust findings reveal complex vACC connectivity alterations in bipolar illness, which suggest differences depending on co-occurrence of lifetime psychosis. The similarities in vACC connectivity patterns in schizophrenia and psychotic bipolar disorder patients may suggest the existence of common mechanisms underlying psychotic symptoms in the two disorders.
Altered resting state functional connectivity of the amygdala in bipolar disorder
Young males are often associated with more violence, leading to some serious negative consequences. However, the physiology and the neuroimaging patterns underlying juvenile violence remain unclear. Of the limited knowledge on juvenile violence, the default mode network has been known to be associated with its pathophysiology. This study aimed to investigate functional connectivity alterations of the default mode network in male juvenile violent offenders. 31 juvenile violent offenders in a high-security facility, who were convicted of aggressive behaviors by court, and 28 normal controls from a middle school were recruited as participants. They underwent a resting-state functional magnetic resonance imaging scan. And independent component analysis approaches were used to analyze their data. Compared to the normal controls, the juvenile violent offenders showed a different default mode network pattern, with the functional connectivity increased in the posterior cingulate, and decreased in the right middle temporal, left angular, right precuneus and right middle frontal cortex. Our findings revealed that the male juvenile violent offenders were associated with abnormal default mode network functional connectivity, which might be a neuroimaging basis for their tendency to violence.