Functional Connectivity In Areas Research Articles

Neuroimaging studies of resting-state functional magnetic resonance imaging in eating disorders

Eating disorders (EDs), including anorexia nervosa (AN), bulimia nervosa (BN), binge-eating disorder (BED), and pica, are psychobehavioral conditions characterized by abnormal eating behaviors and an excessive preoccupation with weight and body shape. This review examines changes in brain regions and functional connectivity in ED patients over the past decade (2013–2023) using resting-state functional magnetic resonance imaging (rs-fMRI). Key findings highlight alterations in brain networks such as the default mode network (DMN), central executive network (CEN), and emotion regulation network (ERN). In individuals with AN, there is reduced functional connectivity in areas associated with facial information processing and social cognition, alongside increased connectivity in regions linked to sensory stimulation, aesthetic judgment, and social anxiety. Conversely, BED patients show diminished connectivity in the dorsal anterior cingulate cortex within the salience network and increased connectivity in the posterior cingulate cortex and medial prefrontal cortex within the DMN. These findings suggest that rs-fMRI could serve as a valuable biomarker for assessing brain function and predicting treatment outcomes in EDs, paving the way for personalized therapeutic strategies.

TMS-Induced Modulation of EEG Functional Connectivity Is Affected by the E-Field Orientation.

Coregistration of transcranial magnetic stimulation (TMS) and electroencephalography (EEG) allows non-invasive probing of brain circuits: TMS induces brain activation due to the generation of a properly oriented focused electric field (E-field) using a coil placed on a selected position over the scalp, while EEG captures the effects of the stimulation on brain electrical activity. Moreover, the combination of these techniques allows the investigation of several brain properties, including brain functional connectivity. The choice of E-field parameters, such as intensity, orientation, and position, is crucial for eliciting cortex-specific effects. Here, we evaluated whether and how the spatial pattern, i.e., topography and strength of functional connectivity, is modulated by the stimulus orientation. We systematically altered the E-field orientation when stimulating the left pre-supplementary motor area and showed an increase of functional connectivity in areas associated with the primary motor cortex and an E-field orientation-specific modulation of functional connectivity intensity.

Fluid intelligence and its neural correlates in early onset mild cognitive impairment

AbstractBackgroundFluid intelligence refers to the ability of abstract reasoning, problem‐solving and other mental activities considered to be independent from learned knowledges and experience. It has been demonstrated that fluid intelligence is compromised in Mild Cognitive Impairment (MCI), but it also declines with ageing. We tested if fluid intelligence is also affected when MCI occurs before 65 years of age (i.e., in early‐onset MCI) and studied its specific functional and structural brain correlates independently from the effect of ageing.MethodEighty‐five subjects with early‐onset MCI (cognitive symptoms onset < 65 years) underwent extended neuropsychological assessment including Raven’s Coloured Progressive Matrices (RCPM), a culture‐free non‐verbal relational reasoning task that is considered a proxy of fluid intelligence. They also underwent multimodal Magnetic Resonance Imaging (MRI) protocol on a 3T scanner including high‐resolution T1 and sequences acquired at rest for functional MRI (fMRI). Performance at RCPM was related to regional grey matter volume using Voxel Based Morphometry (VBM) and to functional connectivity of resting‐state networks (RSNs) known to be related to cognition using independent component analysis.ResultsThe median RCPM score was 27 (range 8‐36, with 36 being the maximum obtainable score). Among all 85 patients, only 11.8% (N=10) performed below the age and education‐corrected cut‐off. These patients also had significantly lower scores in almost all the remaining neuropsychological tests, suggesting that they were in a more severe stage of MCI (i.e., close to conversion). VBM results showed that, across all patients, decreased performance on RCPM was associated with focal atrophy in right fronto‐temporal and bilateral parietal areas (Figure 1). FMRI acquired at rest showed that better performance on RCPM was associated with lower functional connectivity in areas of the anterior DMN and with higher functional connectivity in areas of the left fronto‐parietal RSN (also indicated as the working memory RSN).ConclusionIn patients with early‐onset MCI fluid intelligence is relatively preserved, associated with lower atrophy in right fronto‐temporal and bilateral parietal regions, and with decreased functional connectivity in the anterior DMN and increased in the left fronto‐parietal network.

Patterns of default mode network in temporal lobe epilepsy with and without hippocampal sclerosis

The default mode network (DMN) consists of the deactivation of specific regions during the performance of cognitive tasks and activation during resting or mind wandering. Several pieces of evidence indicate the impairment of DMN in patients with mesial temporal lobe epilepsy (MTLE). However, most of these studies combined different underlying etiologies, failing to disentangle the influence of seizures and presence and side of hippocampal sclerosis (HS). We included 119 patients with MTLE divided into right-HS (n = 42), left-HS (n = 46), and magnetic resonance imaging (MRI)-negative MTLE (n = 31) and controls (n = 59). All underwent resting-state seed-based functional connectivity (FC), with a seed placed at the posterior cingulate cortex (PCC), an essential node for the DMN. To access group inferences, we used an SPM (Statistical Parametric Mapping) full-factorial model to compare patterns of activation using pairwise comparisons among all groups. Our results indicate a different pattern of DMN FC when controlling for side and presence of HS. The group with right-HS had increased FC in the left angular gyrus and the left middle occipital gyrus, when compared to controls, and increased FC of the left hippocampus when compared to the group with left-HS. The MRI-negative group had increased FC of the left hippocampus, left ventral diencephalon, and left fusiform gyrus as compared to left-HS, but did not show any areas of reduced FC compared to controls. By contrast, the group with left-HS did not show areas of increased FC compared to controls or the right-HS and had reduced FC in the left hippocampus compared to controls. Hence, the right-HS presented increased FC in areas related to the DMN in the left hemisphere; the MRI-negative group also showed increased FC in left-sided structures close to temporal lobe when compared to left-HS, probably indicating engagement in a compensatory system. In a subanalysis considering only the MRI-negative with left-sided EEG (electroencephalogram) subgroup, we found differences against controls, with left angular gyrus more connected in the first group, but no significant differences when compared to the group with left-HS. We conclude that the origin of seizures on the left hemisphere seems to engender a less prominent capacity of recruiting other neighbor areas related to DMN as compared to right-HS and controls. Considering recent studies that have revealed the importance of DMN for cognitive skills and memory, our findings may indicate that deficiencies exhibited by patients with left-HS temporal lobe epilepsy (TLE) in connecting to the DMN could be a surrogate marker of their known worse neuropsychological performance. Further studies with direct comparisons between cognitive tests and FC within the DMN are needed to validate these findings, especially for MRI-negative patients.This article is part of the Special Issue “NEWroscience 2018”

Stage-dependent remodeling of projections to motor cortex in ALS mouse model revealed by a new variant retrograde-AAV9.

Amyotrophic lateral sclerosis (ALS) is characterized by the progressive degeneration of motoneurons in the primary motor cortex (pMO) and in spinal cord. However, the pathogenic process involves multiple subnetworks in the brain and functional MRI studies demonstrate an increase in functional connectivity in areas connected to pMO despite the ongoing neurodegeneration. The extent and the structural basis of the motor subnetwork remodeling in experimentally tractable models remain unclear. We have developed a new retrograde AAV9 to quantitatively map the projections to pMO in the SOD1(G93A) ALS mouse model. We show an increase in the number of neurons projecting from somatosensory cortex to pMO at presymptomatic stages, followed by an increase in projections from thalamus, auditory cortex and contralateral MO (inputs from 20 other structures remains unchanged) as disease advances. The stage- and structure-dependent remodeling of projection to pMO in ALS may provide insights into the hyperconnectivity observed in ALS patients.

Functional brain changes in auditory phantom perception evoked by different stimulus frequencies

Bayesian models of brain function such as active inference and predictive coding offer a general theoretical framework with which to explain several aspects of normal and disordered brain function. Of particular interest to the present study is the potential for such models to explain the pathology of auditory phantom perception, i.e. tinnitus. To test this framework empirically, we perform an fMRI experiment on a large clinical sample (n = 75) of the human chronic tinnitus population. The experiment features a within-subject design based on two experimental conditions: subjects were presented with sound stimuli matched to their tinnitus frequency (TF) as well as similar stimuli presented at a control frequency (CF). The responses elicited by these stimuli, as measured using both activity and functional connectivity, were then analyzed both within and between conditions. Given the Bayesian-brain framework, we hypothesize that TF stimuli will elicit greater activity and/or functional connectivity in areas related to the cognitive and emotional aspects of tinnitus, i.e. tinnitus-related distress. We conversely hypothesize that CF stimuli will elicit greater activity/connectivity in areas related to auditory perception and attention. We discuss our results in the context of this framework and suggest future directions for empirical testing.

Impulsive-antisocial psychopathic traits linked to increased volume and functional connectivity within prefrontal cortex.

Psychopathy is a personality disorder characterized by callous lack of empathy, impulsive antisocial behavior, and criminal recidivism. Studies of brain structure and function in psychopathy have frequently identified abnormalities in the prefrontal cortex. However, findings have not yet converged to yield a clear relationship between specific subregions of prefrontal cortex and particular psychopathic traits. We performed a multimodal neuroimaging study of prefrontal cortex volume and functional connectivity in psychopathy, using a sample of adult male prison inmates (N = 124). We conducted volumetric analyses in prefrontal subregions, and subsequently assessed resting-state functional connectivity in areas where volume was related to psychopathy severity. We found that overall psychopathy severity and Factor 2 scores (which index the impulsive/antisocial traits of psychopathy) were associated with larger prefrontal subregion volumes, particularly in the medial orbitofrontal cortex and dorsolateral prefrontal cortex. Furthermore, Factor 2 scores were also positively correlated with functional connectivity between several areas of the prefrontal cortex. The results were not attributable to age, race, IQ, substance use history, or brain volume. Collectively, these findings provide evidence for co-localized increases in prefrontal cortex volume and intra-prefrontal functional connectivity in relation to impulsive/antisocial psychopathic traits.

Perceived social isolation is associated with altered functional connectivity in neural networks associated with tonic alertness and executive control

Perceived social isolation (PSI), colloquially known as loneliness, is associated with selectively altered attentional, cognitive, and affective processes in humans, but the neural mechanisms underlying these adjustments remain largely unexplored. Behavioral, eye tracking, and neuroimaging research has identified associations between PSI and implicit hypervigilance for social threats. Additionally, selective executive dysfunction has been evidenced by reduced prepotent response inhibition in social Stroop and dichotic listening tasks. Given that PSI is associated with pre-attentional processes, PSI may also be related to altered resting-state functional connectivity (FC) in the brain. Therefore, we conducted the first resting-state fMRI FC study of PSI in healthy young adults. Five-minute resting-state scans were obtained from 55 participants (31 females). Analyses revealed robust associations between PSI and increased brain-wide FC in areas encompassing the right central operculum and right supramarginal gyrus, and these associations were not explained by depressive symptomatology, objective isolation, or demographics. Further analyses revealed that PSI was associated with increased FC between several nodes of the cingulo-opercular network, a network known to underlie the maintenance of tonic alertness. These regions encompassed the bilateral insula/frontoparietal opercula and ACC/pre-SMA. In contrast, FC between the cingulo-opercular network and right middle/superior frontal gyrus was reduced, a finding associated with diminished executive function in prior literature. We suggest that, in PSI, increased within-network cingulo-opercular FC may be associated with hypervigilance to social threat, whereas reduced right middle/superior frontal gyrus FC to the cingulo-opercular network may be associated with diminished impulse control.

Impulsive-Antisocial Dimension of Psychopathy Linked to Enlargement and Abnormal Functional Connectivity of the Striatum

BackgroundPsychopathy is a mental health disorder characterized by callous and impulsive antisocial behavior, and it is associated with a high incidence of violent crime, substance abuse, and recidivism. Recent studies suggest that the striatum may be a key component of the neurobiological basis for the disorder, although structural findings have been mixed, and functional connectivity of the striatum in psychopathy has yet to be fully examined. MethodsWe performed a multimodal neuroimaging study of striatum volume and functional connectivity in psychopathy using a large sample of adult male prison inmates (N = 124). We conducted volumetric analyses in striatal subnuclei and subsequently assessed resting-state functional connectivity in areas where volume was related to psychopathy severity. ResultsTotal Psychopathy Checklist–Revised and factor 2 scores (which index the impulsive-antisocial traits of psychopathy) were associated with larger striatal subnuclei volumes and increased volume in focal areas throughout the striatum, particularly in the nucleus accumbens and putamen bilaterally. Furthermore, at many of the striatal areas where volume was positively associated with factor 2 scores, psychopathy severity was also associated with abnormal functional connectivity with other brain regions, including dorsolateral prefrontal cortex, ventral midbrain, and other areas of the striatum. The results were not attributable to age, race, IQ, substance use history, or intracranial volume. ConclusionsThese findings associate the impulsive-antisocial dimension of psychopathy with enlarged striatal subnuclei and aberrant functional connectivity between the striatum and other brain regions. Furthermore, the colocalization of volumetric and functional connectivity findings suggests that these neural abnormalities may be pathophysiologically linked.

Effects of seven-day diazepam administration on resting-state functional connectivity in healthy volunteers: a randomized, double-blind study.

Benzodiazepines, such as diazepam, are anxiolytic-sedative drugs, used for the treatment of several different disorders. The pharmacological mechanism of action of benzodiazepines is well understood; however, it remains unclear which neural networks and systems are involved in translating these neurochemical actions into their therapeutic effects. The objective of this study was to investigate the effects of 7-day diazepam administration compared to placebo on resting-state functional connectivity in healthy adults independent of any task. Thirty-four healthy participants were randomly assigned to receive either diazepam (N = 17) or placebo (15mg daily for 7days) and underwent resting-state functional magnetic resonance acquisition. Model-free data analysis was performed using independent component analysis and dual regression. Consistent with previous research, 11 resting-state networks were identified. Increased connectivity in response to diazepam administration was found in the medial visual network and middle/inferior temporal network. Diazepam did not cause any decreases in functional connectivity. Diazepam administration increases functional connectivity in areas of emotional processing independent of any task. Diazepam also enhanced functional connectivity in the medial visual system, which is a brain region rich in GABAA receptors, and shows high binding of GABAergic drugs. These increases in functional connectivity are characteristic of CNS depressants.

Additional resources and the default mode network: Evidence of increased connectivity and decreased white matter integrity in amyotrophic lateral sclerosis

In amyotrophic lateral sclerosis (ALS), cognition is affected. Cortical atrophy in frontal and temporal areas has been associated with the cognitive profile of patients. Additionally, reduced metabolic turnover and regional cerebral blood flow in frontal areas indicative of reduced neural activity have been reported for ALS. We hypothesize that functional connectivity in non-task associated functional default mode network (DMN) is associated with cognitive profile and white matter integrity. This study focused on specific cognitive tasks known to be impaired in ALS such as verbal fluency and attention, and the relationship with functional connectivity in the DMN and white matter integrity. Nine patients and 11 controls were measured with an extensive neuropsychological battery. Resting-state functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) data were acquired. Results showed that ALS patients performed significantly worse in attention and verbal fluency task. Patients showed increased functional connectivity in parahippocampal and parietal areas of the non-task associated DMN compared to controls. The more pronounced the cognitive deficits, the stronger the increase in functional connectivity in those areas. White matter integrity was reduced in frontal areas in the patients. In conclusion, increased connectivity in the DMN in parahippocampal and parietal areas might represent recruitment of accessory brain regions to compensate for dysfunctional frontal networks.

EPA-1793 – Enhancement of right hemisphere eeg functional connectivity after emdr therapy

Introduction Brain connectivity changes have been recently demonstrated in victims of psychological traumas treated with the eye movement desensitization and reprocessing (EMDR). Objectives Forty victims of psychological traumas were investigated at the first EMDR session (t0) and at the last one performed after processing the index trauma (t1). Aims To investigate differences in EEG functional source connectivity during bilateral ocular stimulation (BS) during EMDR therapy at t0 and t1. Methods Brain electrical activity during whole EMDR sessions was record with a 37-channel EEG. EEG functional connectivity analysis was based on the lagged phase synchronization (LPS), derived by a two-step eLoreta procedure: dimensionality reduction of inverse matrix from 6239 voxels to 28 regions of interest (ROIs); LPS index computation, for each spectrum band, in all possible ROI pairs. Results Significant differences were detected between t0 and t1 in alpha band LPS indexes. A prevalent enhancement in right intrahemispheric functional connectivity was found in t1 respect to t0, particularly among ROI pairs of (a) frontal regions (anterior frontal, orbital frontal, lateral frontal cortices) and limbic structures (anterior cingulate cortex, ACC), (b) frontal regions and associative areas (insula cortex, parietal lobe), (c) ACC and primary visual cortex and (d) ACC and associative areas. Conclusions These findings suggest that EMDR efficacy is associated to electrical brain connectivity changes during BS. An enhancement in the right hemisphere alpha band functional connectivity of areas involved in cognitive control, emotional processing and visual associative functions may play a key role in the elaboration of psychological traumas.

Functional connectivity in patients with idiopathic generalized epilepsy

Idiopathic generalized epilepsy (IGE) is characterized by electroencephalography (EEG) recordings with generalized spike wave discharges (GSWDs) arising from normal background activity. Although GSWDs are the result of highly synchronized activity in the thalamocortical network, EEG without GSWDs is believed to represent normal brain activity. The aim of this study was to investigate whether thalamocortical interactions are altered even during GSWD-free EEG periods in patients with IGE. A GSWD-related group analysis was performed in 12 IGE patients to define seeds in areas involved during GSWDs. EEG-functional magnetic resonance imaging (fMRI) datasets from 22 IGE patients without GSWDs during the investigation and 30 age-matched healthy controls were then selected to investigate functional connectivity in GSWD-related areas. Blood oxygen level dependent (BOLD) signal changes were extracted from seeds defined by the GSWD-related group analysis. The averaged time course within each seed was used to detect brain regions with BOLD signal correlated with the seed. Group differences between patients and controls were estimated. The GSWD-related group analysis showed BOLD activation in the thalamus, the frontomesial cortex, and the cerebellum and BOLD deactivation in default mode areas. For the connectivity analysis, eight seeds were placed bilaterally in the thalamus, mesial frontal cortex, precuneus, and cerebellum. The functional connectivity analysis of these seeds did not show clearly altered functional connectivity for patients versus controls. The results underscore the paroxysmal nature of GSWDs: Although GSWDs are characterized by highly synchronized activity in the thalamocortical network, the functional connectivity in areas involved during GSWDs does not demonstrate abnormality in GSWD-free periods.

Increased default mode network connectivity associated with meditation

Areas associated with the default mode network (DMN) are substantially similar to those associated with meditation practice. However, no studies on DMN connectivity during resting states have been conducted on meditation practitioners. It was hypothesized that meditators would show heightened functional connectivity in areas of cortical midline activity. Thirty-five meditation practitioners and 33 healthy controls without meditation experience were included in this study. All subjects received 4.68-min resting state functional scanning runs. The posterior cingulate cortex and medial prefrontal cortex were chosen as seed regions for the DMN map. Meditation practitioners demonstrated greater functional connectivity within the DMN in the medial prefrontal cortex area (xyz=339−21) than did controls. These results suggest that the long-term practice of meditation may be associated with functional changes in regions related to internalized attention even when meditation is not being practiced.

A mismatch of scales: challenges in planning for implementation of marine protected areas in the Coral Triangle

AbstractRegional systematic conservation planning is an effective approach to marine protected area (MPA) network design, ensuring complementarity, and functional connectivity of areas. However, regional planning and local conservation actions do not properly inform one another. One outcome is the failure of regional designs to guide conservation actions. Another is that site‐based MPAs constitute collections rather than functional systems for marine conservation. Understanding decisions related to spatial scale in conservation planning is essential for the development of ecologically functional networks of MPAs. Decisions about scale require that planners address trade‐offs between the respective advantages and limitations of different considerations in several parts of the planning process. We provide the first comprehensive review of decisions about spatial scale that influence planning outcomes. We illustrate these decisions and the trade‐offs involved with planning exercises undertaken in the Coral Triangle. We provide a framework in which decisions about spatial scale can be made explicit and investigated further. The framework helps to link theory and application in conservation planning, facilitates learning, and promotes the application of conservation actions that are both regionally and locally significant.