scholarly journals Frequency-Specific Changes in the Fractional Amplitude of the Low-Frequency Fluctuations in the Default Mode Network in Medication-Free Patients With Bipolar II Depression: A Longitudinal Functional MRI Study

2021 ◽  
Vol 11 ◽  
Author(s):  
Jun Zhou ◽  
Xiaoqian Ma ◽  
Chunwang Li ◽  
Aijun Liao ◽  
Zihao Yang ◽  
...  
Keyword(s):  
Default Mode Network ◽  
Rating Scale ◽  
Low Frequency ◽  
Anterior Cingulate ◽  
Depression Symptoms ◽  
Superior Frontal Gyrus ◽  
Default Mode ◽  
Bipolar Ii ◽  
Frequency Fluctuations

Objective: This study aimed to examine the treatment-related changes of the fractional amplitude of low-frequency fluctuations (fALFF) in the default mode network (DMN) across different bands after the medication-free patients with bipolar II depression received a 16-week treatment of escitalopram and lithium.Methods: A total of 23 medication-free patients with bipolar II depression and 29 healthy controls (HCs) were recruited. We evaluated the fALFF values of slow 4 (0.027–0.073 Hz) band and slow 5 (0.01–0.027 Hz) band of the patients and compared the results with those of the 29 HCs at baseline. After 16-week treatment of escitalopram with lithium, the slow 4 and slow 5 fALFF values of the patients were assessed and compared with the baselines of patients and HCs. The depressive symptoms of bipolar II depression in patients were assessed with a 17-item Hamilton Depression Rating Scale (HDRS) before and after treatment.Results: Treatment-related effects showed increased slow 5 fALFF in cluster D (bilateral medial superior frontal gyrus, bilateral superior frontal gyrus, right middle frontal gyrus, and bilateral anterior cingulate), cluster E (bilateral precuneus/posterior cingulate, left cuneus), and cluster F (left angular, left middle temporal gyrus, left superior temporal gyrus, and left supramarginal gyrus) in comparison with the baseline of the patients. Moreover, a positive association was found between the increase in slow 5 fALFF values (follow-up value minus the baseline values) in cluster D and the decrease in HDRS scores (baseline HDRS scores minus follow-up HDRS scores) at follow-up, and the same association between the increase in slow 5 fALFF values and the decrease in HDRS scores was found in cluster E.Conclusions: The study reveals that the hypoactivity of slow 5 fALFF in the DMN is related to depression symptoms and might be corrected by the administration of escitalopram with lithium, implying that slow 5 fALFF of the DMN plays a key role in bipolar depression.

Multimorbidity and Regional Volumes of the Default Mode Network in Brain Aging

Gerontology ◽  
2021 ◽  
pp. 1-10
Author(s):  
Jen-Hung Wang ◽  
Joshua Oon Soo Goh ◽  
Yu-Ling Chang ◽  
Shu-Cin Chen ◽  
Yu-Ying Li ◽  
...  
Keyword(s):  
Default Mode Network ◽  
Structural Integrity ◽  
Rating Scale ◽  
Brain Aging ◽  
Fasting Blood Glucose ◽  
Cingulate Cortex ◽  
Anterior Cingulate ◽  
Cross Sectional ◽  
Default Mode ◽  
Posterior Cingulate

<b><i>Introduction:</i></b> The default mode network (DMN) is selectively vulnerable in brain aging. Little is known about the effect of multimorbidity as a whole onto the brain structural integrity. <b><i>Objective:</i></b> We aimed to investigate the association between multimorbidity and the structural integrity of DMN. <b><i>Methods:</i></b> We enrolled senior volunteers aged between 60 and 80 years in Hualien County during 2014–2018 and conducted in-person interview to collect information on chronic diseases. Fasting blood glucose and glycated hemoglobin (HbA1c) were tested. We assessed multimorbidity burden by the cumulative illness rating scale-geriatric (CIRS-G). MRI brain scans were standardized to measure the regional volume within the DMN. In a cross-sectional design, we employed stepwise regression models to evaluate the effects of age, sex, hyperglycemia, and multimorbidity on the DMN. <b><i>Results:</i></b> A total of 170 volunteers were enrolled with a mean age of 66.9 years, female preponderance (71%), an average mini-mental state examination score of 27.6, a mean HbA1c of 6.0, and a mean CIRS-G total score (TS) of 7.2. We found that older age was associated with reduced volumes in the hippocampus, left rostral anterior cingulate cortex, right posterior cingulate, right isthmus, precuneus, and right supramarginal. Higher levels of HbA1c and fasting glucose were associated with a reduced volume in the hippocampus only. A higher CIRS-G-TS was associated with reduced volumes in the left posterior cingulate cortex and right supramarginal gyrus; while a higher CIRS-G severity index was associated with a smaller right precuneus and right supramarginal. <b><i>Conclusions:</i></b> In the DMN, hippocampal volume shows vulnerability to aging and hyperglycemia, whereas the posterior cingulate, supramarginal, and precuneus cortices may be the key sites to reflect the total effects of multimorbidity.

scholarly journals Task-Related Modulations of BOLD Low-Frequency Fluctuations within the Default Mode Network

2017 ◽  
Vol 5 ◽  
Author(s):  
Silvia Tommasin ◽  
Daniele Mascali ◽  
Tommaso Gili ◽  
Ibrahim Eid Assan ◽  
Marta Moraschi ◽  
...  
Keyword(s):  
Default Mode Network ◽  
Low Frequency ◽  
Default Mode ◽  
Frequency Fluctuations

Default mode network shows alterations for low-frequency fMRI fluctuations in euthymic bipolar disorder

2021 ◽  
Author(s):  
Marco Marino ◽  
Zaira Romeo ◽  
Alessandro Angrilli ◽  
Ilaria Semenzato ◽  
Angela Favaro ◽  
...  
Keyword(s):  
Bipolar Disorder ◽  
Default Mode Network ◽  
Low Frequency ◽  
Default Mode

scholarly journals Aberrant Dynamic Functional Connectivity of Default Mode Network in Schizophrenia and Links to Symptom Severity

2021 ◽  
Vol 15 ◽  
Author(s):  
Mohammad S. E. Sendi ◽  
Elaheh Zendehrouh ◽  
Charles A. Ellis ◽  
Zhijia Liang ◽  
Zening Fu ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Default Mode Network ◽  
Resting State ◽  
Symptom Severity ◽  
Transition Probability ◽  
Feature Selection Method ◽  
Cingulate Cortex ◽  
Anterior Cingulate ◽  
Dynamic Functional Connectivity ◽  
Default Mode

Background: Schizophrenia affects around 1% of the global population. Functional connectivity extracted from resting-state functional magnetic resonance imaging (rs-fMRI) has previously been used to study schizophrenia and has great potential to provide novel insights into the disorder. Some studies have shown abnormal functional connectivity in the default mode network (DMN) of individuals with schizophrenia, and more recent studies have shown abnormal dynamic functional connectivity (dFC) in individuals with schizophrenia. However, DMN dFC and the link between abnormal DMN dFC and symptom severity have not been well-characterized.Method: Resting-state fMRI data from subjects with schizophrenia (SZ) and healthy controls (HC) across two datasets were analyzed independently. We captured seven maximally independent subnodes in the DMN by applying group independent component analysis and estimated dFC between subnode time courses using a sliding window approach. A clustering method separated the dFCs into five reoccurring brain states. A feature selection method modeled the difference between SZs and HCs using the state-specific FC features. Finally, we used the transition probability of a hidden Markov model to characterize the link between symptom severity and dFC in SZ subjects.Results: We found decreases in the connectivity of the anterior cingulate cortex (ACC) and increases in the connectivity between the precuneus (PCu) and the posterior cingulate cortex (PCC) (i.e., PCu/PCC) of SZ subjects. In SZ, the transition probability from a state with weaker PCu/PCC and stronger ACC connectivity to a state with stronger PCu/PCC and weaker ACC connectivity increased with symptom severity.Conclusions: To our knowledge, this was the first study to investigate DMN dFC and its link to schizophrenia symptom severity. We identified reproducible neural states in a data-driven manner and demonstrated that the strength of connectivity within those states differed between SZs and HCs. Additionally, we identified a relationship between SZ symptom severity and the dynamics of DMN functional connectivity. We validated our results across two datasets. These results support the potential of dFC for use as a biomarker of schizophrenia and shed new light upon the relationship between schizophrenia and DMN dynamics.

scholarly journals Basal forebrain contributes to default mode network regulation

2018 ◽  
Vol 115 (6) ◽  
pp. 1352-1357 ◽  
Author(s):  
Jayakrishnan Nair ◽  
Arndt-Lukas Klaassen ◽  
Jozsef Arato ◽  
Alexei L. Vyssotski ◽  
Michael Harvey ◽  
...  
Keyword(s):  
Default Mode Network ◽  
Basal Forebrain ◽  
Cognitive Task ◽  
Gamma Oscillations ◽  
Anterior Cingulate ◽  
Gamma Activity ◽  
Sensory Stimuli ◽  
Quiet Wakefulness ◽  
Default Mode ◽  
Brain States

The default mode network (DMN) is a collection of cortical brain regions that is active during states of rest or quiet wakefulness in humans and other mammalian species. A pertinent characteristic of the DMN is a suppression of local field potential gamma activity during cognitive task performance as well as during engagement with external sensory stimuli. Conversely, gamma activity is elevated in the DMN during rest. Here, we document that the rat basal forebrain (BF) exhibits the same pattern of responses, namely pronounced gamma oscillations during quiet wakefulness in the home cage and suppression of this activity during active exploration of an unfamiliar environment. We show that gamma oscillations are localized to the BF and that gamma-band activity in the BF has a directional influence on a hub of the rat DMN, the anterior cingulate cortex, during DMN-dominated brain states. The BF is well known as an ascending, activating, neuromodulatory system involved in wake–sleep regulation, memory formation, and regulation of sensory information processing. Our findings suggest a hitherto undocumented role of the BF as a subcortical node of the DMN, which we speculate may be important for switching between internally and externally directed brain states. We discuss potential BF projection circuits that could underlie its role in DMN regulation and highlight that certain BF nuclei may provide potential target regions for up- or down-regulation of DMN activity that might prove useful for treatment of DMN dysfunction in conditions such as epilepsy or major depressive disorder.

scholarly journals Effects of the DRD4 −521 C/T SNP on Local Neural Activity and Functional Connectivity in Children With ADHD

2022 ◽  
Vol 12 ◽  
Author(s):  
Huan Zhang ◽  
Binrang Yang ◽  
Gang Peng ◽  
Linlin Zhang ◽  
Diangang Fang
Keyword(s):  
Functional Connectivity ◽  
Brain Function ◽  
Rating Scale ◽  
Low Frequency ◽  
Regional Homogeneity ◽  
Frequency Fluctuation ◽  
Behavioral Performance ◽  
Superior Frontal Gyrus ◽  
Middle Occipital Gyrus ◽  
The Right

Objective: The present study aimed to investigate the effects of the dopamine receptor D4 (DRD4) −521 C/T single-nucleotide polymorphism on brain function among children with attention deficit hyperactivity disorder (ADHD) and to evaluate whether brain function is associated with behavioral performance among this demographic.Methods: Using regional homogeneity, fractional amplitude low-frequency fluctuation, and functional connectivity as measurement indices, we compared differences in resting-state brain function between 34 boys with ADHD in the TT homozygous group and 37 boys with ADHD in the C-allele carrier group. The Conners' Parent Rating Scale, the SNAP-IV Rating Scale, the Stroop Color Word Test, the go/no-go task, the n-back task, and the working memory index within the Wechsler Intelligence Scale for Children-Fourth Edition were selected as comparative indicators in order to test effects on behavioral performance.Results: We found that TT homozygotes had low behavioral performance as compared with C-allele carriers. The regional homogeneity for TT homozygotes decreased in the right middle occipital gyrus and increased in the right superior frontal gyrus as compared with C-allele carriers. In addition, the right middle occipital gyrus and the right superior frontal gyrus were used as the seeds of functional connectivity, and we found that the functional connectivity between the right middle occipital gyrus and the right cerebellum decreased, as did the functional connectivity between the right superior frontal gyrus and the angular gyrus. No statistically significant differences were observed in the respective brain regions when comparing the fractional amplitudes for low-frequency fluctuation between the two groups. Correlation analyses demonstrated that the fractional amplitude low-frequency fluctuation in the precentral gyrus for TT homozygotes were statistically significantly correlated with working memory.Conclusions: We found differing effects of DRD4 −521 C/T polymorphisms on brain function among boys with ADHD. These findings promote our understanding of the genetic basis for neurobiological differences observed among children with ADHD, but they must be confirmed in larger samples.

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