Fractal analysis of resting state functional connectivity of the brain

Introduction: There is growing scientific interest in understanding the biological mechanisms affecting and/or underlying violent behaviors in order to develop effective treatment and prevention programs. In recent years, neuroscientific research has tried to demonstrate whether the intrinsic activity within the brain at rest in the absence of any external stimulation (resting-state functional connectivity; RSFC) could be employed as a reliable marker for several cognitive abilities and personality traits that are important in behavior regulation, particularly, proneness to violence. Aims: This review aims to highlight the association between the RSFC among specific brain structures and the predisposition to experiencing anger and/or responding to stressful and distressing situations with anger in several populations. Methods: The scientific literature was reviewed following the PRISMA quality criteria for reviews, using the following digital databases: PubMed, PsycINFO, Psicodoc, and Dialnet. Results: The identification of 181 abstracts and retrieval of 34 full texts led to the inclusion of 17 papers. The results described in our study offer a better understanding of the brain networks that might explain the tendency to experience anger. The majority of the studies highlighted that diminished RSFC between the prefrontal cortex and the amygdala might make people prone to reactive violence, but that it is also necessary to contemplate additional cortical (i.e. insula, gyrus [angular, supramarginal, temporal, fusiform, superior, and middle frontal], anterior and posterior cingulated cortex) and subcortical brain structures (i.e. hippocampus, cerebellum, ventral striatum, and nucleus centralis superior) in order to explain a phenomenon as complex as violence. Moreover, we also described the neural pathways that might underlie proactive violence and feelings of revenge, highlighting the RSFC between the OFC, ventral striatal, angular gyrus, mid-occipital cortex, and cerebellum. Conclusions. The results from this synthesis and critical analysis of RSFC findings in several populations offer guidelines for future research and for developing a more accurate model of proneness to violence, in order to create effective treatment and prevention programs.

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Presurgical Evaluation of Epilepsy Using Resting-State MEG Functional Connectivity

Frontiers in Human Neuroscience ◽

10.3389/fnhum.2021.649074 ◽

2021 ◽

Vol 15 ◽

Author(s):

Na Xu ◽

Wei Shan ◽

Jing Qi ◽

Jianping Wu ◽

Qun Wang

Keyword(s):

Functional Connectivity ◽

Resting State ◽

Preoperative Evaluation ◽

Brain Regions ◽

Electrophysiological Recording ◽

Epileptogenic Zone ◽

Resting State Functional Connectivity ◽

Presurgical Evaluation ◽

Resting State Connectivity ◽

The Brain

Epilepsy is caused by abnormal electrical discharges (clinically identified by electrophysiological recording) in a specific part of the brain [originating in only one part of the brain, namely, the epileptogenic zone (EZ)]. Epilepsy is now defined as an archetypical hyperexcited neural network disorder. It can be investigated through the network analysis of interictal discharges, ictal discharges, and resting-state functional connectivity. Currently, there is an increasing interest in embedding resting-state connectivity analysis into the preoperative evaluation of epilepsy. Among the various neuroimaging technologies employed to achieve brain functional networks, magnetoencephalography (MEG) with the excellent temporal resolution is an ideal tool for estimating the resting-state connectivity between brain regions, which can reveal network abnormalities in epilepsy. What value does MEG resting-state functional connectivity offer for epileptic presurgical evaluation? Regarding this topic, this paper introduced the origin of MEG and the workflow of constructing source–space functional connectivity based on MEG signals. Resting-state functional connectivity abnormalities correlate with epileptogenic networks, which are defined by the brain regions involved in the production and propagation of epileptic activities. This paper reviewed the evidence of altered epileptic connectivity based on low- or high-frequency oscillations (HFOs) and the evidence of the advantage of using simultaneous MEG and intracranial electroencephalography (iEEG) recordings. More importantly, this review highlighted that MEG-based resting-state functional connectivity has the potential to predict postsurgical outcomes. In conclusion, resting-state MEG functional connectivity has made a substantial progress toward serving as a candidate biomarker included in epileptic presurgical evaluations.

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Resting state functional connectivity in the human spinal cord

eLife ◽

10.7554/elife.02812 ◽

2014 ◽

Vol 3 ◽

Cited By ~ 53

Author(s):

Robert L Barry ◽

Seth A Smith ◽

Adrienne N Dula ◽

John C Gore

Keyword(s):

Spinal Cord ◽

Functional Connectivity ◽

Resting State ◽

Low Frequency ◽

Blood Oxygenation ◽

Resting State Functional Connectivity ◽

Human Spinal Cord ◽

Oxygenation Level ◽

Left And Right ◽

The Brain

Functional magnetic resonance imaging using blood oxygenation level dependent (BOLD) contrast is well established as one of the most powerful methods for mapping human brain function. Numerous studies have measured how low-frequency BOLD signal fluctuations from the brain are correlated between voxels in a resting state, and have exploited these signals to infer functional connectivity within specific neural circuits. However, to date there have been no previous substantiated reports of resting state correlations in the spinal cord. In a cohort of healthy volunteers, we observed robust functional connectivity between left and right ventral (motor) horns, and between left and right dorsal (sensory) horns. Our results demonstrate that low-frequency BOLD fluctuations are inherent in the spinal cord as well as the brain, and by analogy to cortical circuits, we hypothesize that these correlations may offer insight into the execution and maintenance of sensory and motor functions both locally and within the cerebrum.

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Injury alters intrinsic functional connectivity within the primate spinal cord

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1424106112 ◽

2015 ◽

Vol 112 (19) ◽

pp. 5991-5996 ◽

Cited By ~ 37

Author(s):

Li Min Chen ◽

Arabinda Mishra ◽

Pai-Feng Yang ◽

Feng Wang ◽

John C. Gore

Keyword(s):

Spinal Cord ◽

Functional Connectivity ◽

Resting State ◽

Low Frequency ◽

Resting State Functional Connectivity ◽

Activation Patterns ◽

Strongly Connected ◽

Unilateral Injury ◽

Entire Central Nervous System ◽

The Brain

Recent demonstrations of correlated low-frequency MRI signal variations between subregions of the spinal cord at rest in humans, similar to those found in the brain, suggest that such resting-state functional connectivity constitutes a common feature of the intrinsic organization of the entire central nervous system. We report our detection of functional connectivity within the spinal cords of anesthetized squirrel monkeys at rest and show that the strength of connectivity within these networks is altered by the effects of injuries. By quantifying the low-frequency MRI signal correlations between different horns within spinal cord gray matter, we found distinct functional connectivity relationships between the different sensory and motor horns, a pattern that was similar to activation patterns evoked by nociceptive heat or tactile stimulation of digits. All horns within a single spinal segment were functionally connected, with the strongest connectivity occurring between ipsilateral dorsal and ventral horns. Each horn was strongly connected to the same horn on neighboring segments, but this connectivity reduced drastically along the spinal cord. Unilateral injury to the spinal cord significantly weakened the strength of the intrasegment horn-to-horn connectivity only on the injury side and in slices below the lesion. These findings suggest resting-state functional connectivity may be a useful biomarker of functional integrity in injured and recovering spinal cords.

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Resting-state functional connectivity in adults with childhood emotional maltreatment

Psychological Medicine ◽

10.1017/s0033291712002942 ◽

2012 ◽

Vol 43 (9) ◽

pp. 1825-1836 ◽

Cited By ~ 67

Author(s):

S. J. A. van der Werff ◽

J. N. Pannekoek ◽

I. M. Veer ◽

M.-J. van Tol ◽

A. Aleman ◽

...

Keyword(s):

Functional Connectivity ◽

Resting State ◽

Cingulate Cortex ◽

Anterior Cingulate ◽

Brain Morphology ◽

Salience Network ◽

Resting State Functional Connectivity ◽

Dorsal Anterior Cingulate Cortex ◽

Emotional Maltreatment ◽

The Brain

BackgroundChildhood emotional maltreatment (CEM) has been associated with disturbances in emotional and behavioral functioning, and with changes in regional brain morphology. However, whether CEM has any effect on the intrinsic organization of the brain is not known. In this study, we investigated the effects of CEM on resting-state functional connectivity (RSFC) using seeds in the limbic network, the default-mode network (DMN) and the salience network, and the left dorsomedial prefrontal cortex (dmPFC).MethodUsing 3-T magnetic resonance imaging (MRI), resting-state functional MRI (RS-fMRI) scans were obtained. We defined seeds in the bilateral amygdala, the dorsal anterior cingulate cortex (dACC), the posterior cingulate cortex (PCC) and the left dmPFC, and used these to examine whether individuals reporting CEM (n=44) differed from individuals reporting no CEM (n=44) in RSFC with other brain regions. The two groups were matched for age, gender, handedness and the presence of psychopathology.ResultsCEM was associated with decreased RSFC between the right amygdala and the bilateral precuneus and a cluster extending from the left insula to the hippocampus and putamen. In addition, CEM was associated with decreased RSFC between the dACC and the precuneus and also frontal regions of the brain.ConclusionsWe found that CEM has a profound effect on RSFC in the limbic network and the salience network. Regions that show aberrant connectivity are related to episodic memory encoding, retrieval and self-processing operations.

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Default(y) Mode Network: Important regions of DMN do not survive alterations in flip angles

10.1101/2020.07.09.196568 ◽

2020 ◽

Author(s):

Ishan Singhal ◽

Abhishek K. Soni ◽

Narayanan Srinivasan

Keyword(s):

Functional Connectivity ◽

Resting State ◽

Posterior Cingulate Cortex ◽

Intrinsic Activity ◽

Bold Signal ◽

Resting State Functional Connectivity ◽

Physiological Noise ◽

Fmri Study ◽

The Brain

AbstractThe default mode network (DMN) is thought to capture intrinsic activity of the brain and has been instrumental in understanding the dynamics of the brain. However, the DMN has not been without critics; both conceptual and empirical. The empirical criticisms caution against physiological noise as a source for the reported connectivity in the DMN. Smaller flip angles (FAs) have been modelled and shown to reduce physiological noise in BOLD signal recordings. A previous functional MRI (fMRI) study with flickering checkerboard stimuli, manipulated FAs to show that activity in the posterior-cingulate cortex (PCC) and precuneus is prone to physiological noise. This raises questions about studies that show activations in these areas (PCC and precuneus) with a fixed FA and the role of these areas in brain networks like DMN. Given the prominent role of PCC and precuneus in DMN, we studied the effect of FAs on the resting-state functional connectivity involving these areas in DMN. We used four FAs and recorded resting-state activity in a 3-T scanner. The results show PCC and precuneus BOLD functional connectivity is inconsistent. We lend support to previous empirical criticisms of DMN, linking its activity to physiological noise. Our results add to concerns about PCC and precuneus related BOLD activity and their putative role in DMN. Alongside previous studies we advocate using smaller flip angles as an empirical tool to investigate physiological noise in fMRI studies.

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