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Altered functional connectivity between emotional and cognitive resting state networks in euthymic bipolar I disorder patients.

Lois G, Linke J, Wessa M - PLoS ONE (2014)

Bottom Line: We compared 30 euthymic bipolar I disorder patients and 35 age- and gender-matched healthy controls.This abnormal connectivity pattern did not correlate with variables related to the clinical course of the disease.The present finding may reflect abnormal integration of affective and cognitive information in ventral-emotional and dorsal-cognitive networks in euthymic bipolar patients.

View Article: PubMed Central - PubMed

Affiliation: Department of Clinical Psychology and Neuropsychology, Institute of Psychology, Johannes Gutenberg-University Mainz, Mainz, Germany.

ABSTRACT
Bipolar disorder is characterized by a functional imbalance between hyperactive ventral/limbic areas and hypoactive dorsal/cognitive brain regions potentially contributing to affective and cognitive symptoms. Resting-state studies in bipolar disorder have identified abnormal functional connectivity between these brain regions. However, most of these studies used a seed-based approach, thus restricting the number of regions that were analyzed. Using data-driven approaches, researchers identified resting state networks whose spatial maps overlap with frontolimbic areas such as the default mode network, the frontoparietal networks, the salient network, and the meso/paralimbic network. These networks are specifically engaged during affective and cognitive tasks and preliminary evidence suggests that functional connectivity within and between some of these networks is impaired in bipolar disorder. The present study used independent component analysis and functional network connectivity approaches to investigate functional connectivity within and between these resting state networks in bipolar disorder. We compared 30 euthymic bipolar I disorder patients and 35 age- and gender-matched healthy controls. Inter-network connectivity analysis revealed increased functional connectivity between the meso/paralimbic and the right frontoparietal network in bipolar disorder. This abnormal connectivity pattern did not correlate with variables related to the clinical course of the disease. The present finding may reflect abnormal integration of affective and cognitive information in ventral-emotional and dorsal-cognitive networks in euthymic bipolar patients. Furthermore, the results provide novel insights into the role of the meso/paralimbic network in bipolar disorder.

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Resting state networks of interest.Illustration of one-sample-t-test maps of the anterior and posterior default mode network, right and left frontoparietal network, the salience network, and the meso/paralimbic network identified in the control (left column) and patient (right column) group. Maps are thresholded at P<0.05 (whole-brain FWE corrected). R, Right.
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pone-0107829-g001: Resting state networks of interest.Illustration of one-sample-t-test maps of the anterior and posterior default mode network, right and left frontoparietal network, the salience network, and the meso/paralimbic network identified in the control (left column) and patient (right column) group. Maps are thresholded at P<0.05 (whole-brain FWE corrected). R, Right.

Mentions: To identify valid RSNs, we first estimated the voxel-wise spatial overlap of the ICs with SPM's standard tissue-type probability maps for gray matter, white matter and cerebrospinal fluid (http://imaging.mrc-cbu.cam.ac.uk/imaging/Templates) using Pearson's correlation (Table S1). Subsequently, group-level ICs were spatially sorted in GIFT toolbox using templates of the RSNs of interest (i.e. DMN, right and left FPN, SN, MPN; Table S1). These templates were based on whole-brain task-based co-activation networks, which were derived from ICA analyses on peak activation coordinates archived in a large neuroimaging database (i.e. BrainMap Database) [21]. On the basis of their spatial overlap with the templates, 6 ICs were identified as RSNs of interest. The DMN was divided into an anterior (aDMN) and a posterior component (pDMN) (Figure 1A and B) and the FPNs comprised of two lateralized components (i.e. right and left) (Figure 1C and D). The MPN and SN were each identified as a single component (Figure 1E and F). The highest voxel-wise spatial overlap between the 6 ICs and the corresponding templates were similar to previously reported values (r = 0.31–0.55; [49], [50]). The last step in the selection procedure was to examine the spectral characteristics of the 6 selected ICs using the same procedure as in Allen and colleagues [18]. For each group-level IC, we estimated the difference between the peak spectral power and minimum spectral power at frequencies to the right of the peak (i.e. dynamic range), and the ratio of the integral of power below 0.10 Hz to the integral of power between 0.15 and 0.25 Hz (i.e. low frequency to high frequency power ratio). Visual inspection of the scatter plot of low frequency to high frequency power ratio versus dynamic range confirmed that all 6 ICs are dominated by frequency fluctuations inside the 0.01–0.1 Hz window (Figure S1).


Altered functional connectivity between emotional and cognitive resting state networks in euthymic bipolar I disorder patients.

Lois G, Linke J, Wessa M - PLoS ONE (2014)

Resting state networks of interest.Illustration of one-sample-t-test maps of the anterior and posterior default mode network, right and left frontoparietal network, the salience network, and the meso/paralimbic network identified in the control (left column) and patient (right column) group. Maps are thresholded at P<0.05 (whole-brain FWE corrected). R, Right.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4208743&req=5

pone-0107829-g001: Resting state networks of interest.Illustration of one-sample-t-test maps of the anterior and posterior default mode network, right and left frontoparietal network, the salience network, and the meso/paralimbic network identified in the control (left column) and patient (right column) group. Maps are thresholded at P<0.05 (whole-brain FWE corrected). R, Right.
Mentions: To identify valid RSNs, we first estimated the voxel-wise spatial overlap of the ICs with SPM's standard tissue-type probability maps for gray matter, white matter and cerebrospinal fluid (http://imaging.mrc-cbu.cam.ac.uk/imaging/Templates) using Pearson's correlation (Table S1). Subsequently, group-level ICs were spatially sorted in GIFT toolbox using templates of the RSNs of interest (i.e. DMN, right and left FPN, SN, MPN; Table S1). These templates were based on whole-brain task-based co-activation networks, which were derived from ICA analyses on peak activation coordinates archived in a large neuroimaging database (i.e. BrainMap Database) [21]. On the basis of their spatial overlap with the templates, 6 ICs were identified as RSNs of interest. The DMN was divided into an anterior (aDMN) and a posterior component (pDMN) (Figure 1A and B) and the FPNs comprised of two lateralized components (i.e. right and left) (Figure 1C and D). The MPN and SN were each identified as a single component (Figure 1E and F). The highest voxel-wise spatial overlap between the 6 ICs and the corresponding templates were similar to previously reported values (r = 0.31–0.55; [49], [50]). The last step in the selection procedure was to examine the spectral characteristics of the 6 selected ICs using the same procedure as in Allen and colleagues [18]. For each group-level IC, we estimated the difference between the peak spectral power and minimum spectral power at frequencies to the right of the peak (i.e. dynamic range), and the ratio of the integral of power below 0.10 Hz to the integral of power between 0.15 and 0.25 Hz (i.e. low frequency to high frequency power ratio). Visual inspection of the scatter plot of low frequency to high frequency power ratio versus dynamic range confirmed that all 6 ICs are dominated by frequency fluctuations inside the 0.01–0.1 Hz window (Figure S1).

Bottom Line: We compared 30 euthymic bipolar I disorder patients and 35 age- and gender-matched healthy controls.This abnormal connectivity pattern did not correlate with variables related to the clinical course of the disease.The present finding may reflect abnormal integration of affective and cognitive information in ventral-emotional and dorsal-cognitive networks in euthymic bipolar patients.

View Article: PubMed Central - PubMed

Affiliation: Department of Clinical Psychology and Neuropsychology, Institute of Psychology, Johannes Gutenberg-University Mainz, Mainz, Germany.

ABSTRACT
Bipolar disorder is characterized by a functional imbalance between hyperactive ventral/limbic areas and hypoactive dorsal/cognitive brain regions potentially contributing to affective and cognitive symptoms. Resting-state studies in bipolar disorder have identified abnormal functional connectivity between these brain regions. However, most of these studies used a seed-based approach, thus restricting the number of regions that were analyzed. Using data-driven approaches, researchers identified resting state networks whose spatial maps overlap with frontolimbic areas such as the default mode network, the frontoparietal networks, the salient network, and the meso/paralimbic network. These networks are specifically engaged during affective and cognitive tasks and preliminary evidence suggests that functional connectivity within and between some of these networks is impaired in bipolar disorder. The present study used independent component analysis and functional network connectivity approaches to investigate functional connectivity within and between these resting state networks in bipolar disorder. We compared 30 euthymic bipolar I disorder patients and 35 age- and gender-matched healthy controls. Inter-network connectivity analysis revealed increased functional connectivity between the meso/paralimbic and the right frontoparietal network in bipolar disorder. This abnormal connectivity pattern did not correlate with variables related to the clinical course of the disease. The present finding may reflect abnormal integration of affective and cognitive information in ventral-emotional and dorsal-cognitive networks in euthymic bipolar patients. Furthermore, the results provide novel insights into the role of the meso/paralimbic network in bipolar disorder.

Show MeSH
Related in: MedlinePlus