Resting-state Connectivity Research Articles

Preliminary evidence for changes in frontoparietal network connectivity in the early abstinence period in alcohol use disorder: a longitudinal resting-state functional magnetic resonance imaging study.

The early abstinence period is a crucial phase in alcohol use disorder (AUD) in which patients have to find a new equilibrium and may start recovery, or conversely, relapse. However, the changes in brain functions during this key period are still largely unknown. We set out to study longitudinal changes in large-scale brain networks during the early abstinence period using resting-state scans. We scanned AUD patients twice in a well-controlled inpatient setting, with the first scan taking place shortly after admission and the second scan 4 weeks (±9 days) later near the end of the treatment period. We studied 37 AUD patients (22 males) and 27 healthy controls (16 males). We focused on three networks that are affected in AUD and underly core symptom dimensions in this disorder: the frontoparietal networks (left and right FPN) and default mode network (DMN). Both the whole brain and within network connectivity of these networks were studied using dual regression. Finally, we explored correlations between these brain networks and various neuropsychological and behavioral measures. In contrast to the controls (Z = -1.081, p = 0.280), the AUD patients showed a decrease in within left FPN connectivity (Z = -2.029, p = 0.042). However, these results did not survive a strict Bonferroni correction. The decrease in left FPN connectivity during the early abstinence period in AUD may reflect an initially upregulated FPN, which recovers to a lower resting-state connectivity level during subsequent weeks of abstinence. The AUD patients showed a trend for a positive association between the change in left FPN connectivity and trait anxiety (rs = 0.303, p = 0.068), and a trend for a negative association between the change in left FPN connectivity and delay discounting (rs = -0.283, p = 0.089) (uncorrected for multiple comparisons). This suggests that the FPN might be involved in top-down control of impulsivity and anxiety, which are important risk factors for relapse. Although there were no statistically significant results (after multiple comparison correction), our preliminary findings encourage further research into the dynamic neuroadaptations during the clinically crucial early abstinence period and could inform future study designs.

Neuromodulation of Executive Dysfunction in Patients with Acute Stroke Using Transcranial Direct Current Stimulation: Study Protocol for a Triple-Blind, Randomized Sham-Controlled Trial

Research on the benefits of non-invasive brain stimulation in stroke patients to improve executive functions is scarce. The objective of this study was to investigate the effectiveness of transcranial direct current stimulation (tDCS) in combination with cognitive training for the rehabilitation of executive functions in acute and subacute stroke patients as well as to explore the underlying physiological mechanisms. A triple-blinded, randomized-controlled clinical trial will be conducted involving 60 stroke patients with frontal or basal ganglia lesions and a Montreal Cognitive Assessment (MoCA) score less than 26. Participants will be randomly assigned to receive active tDCS (anode over the left dorsolateral prefrontal cortex, cathode at the right supraorbital region, 20 min at 2 mA) or sham tDCS in a 1:1 ratio for 10 sessions, followed by targeted executive function training. The primary efficacy outcome will be the MoCA score, while secondary outcomes will include the five-digit test (inhibitory control), the Digit Span Task (working memory), the abbreviated version of the Wisconsin Card Sorting test (cognitive flexibility), modified Rankin scale (functional state), Beck-II depression inventory, apathy evaluation scale, and the WHOQOL-BREF (quality of life), assessed immediately after the intervention and at 1, 3, 6, and 12 months post-intervention. Additionally, resting-state functional connectivity and blood biomarkers, such as neurotrophins, growth factors, and inflammatory molecules, will be evaluated before and after the intervention. This study will contribute to the investigation of the efficacy of tDCS in rehabilitating executive functions in acute and subacute stroke patients. The multidimensional approach utilized in this study, which includes analysis of resting-state connectivity and neuroplasticity-related blood biomarkers, is expected to provide insights into the underlying brain mechanisms involved in the rehabilitation of dysexecutive syndrome.

Resting-state fractal brain connectivity is associated with impaired cognitive performance in healthy aging

Aging affects cognitive functions even in the absence of ongoing pathologies. The neurophysiological basis of age-related cognitive decline (CD), however, is not completely understood. Alterations in both functional brain connectivity and in the fractal scaling of neuronal dynamics have been linked to aging and cognitive performance. Recently, fractal connectivity (FrC) has been proposed — combining the two concepts — for capturing long-term interactions among brain regions. FrC was shown to be influenced by increased mental workload; however, no prior studies investigated how resting-state FrC relates to cognitive performance and plausible CD in healthy aging. We recruited 19 healthy elderly (HE) and 24 young control (YC) participants, who underwent resting-state electroencephalography (EEG) measurements and comprehensive cognitive evaluation using 7 tests of the Cambridge Neurophysiological Test Automated Battery. FrC networks were reconstructed from EEG data using the recently introduced multiple-resampling cross-spectral analysis (MRCSA). Elderly individuals could be characterized with increased response latency and reduced performance in 4–4 tasks, respectively, with both reaction time and accuracy being affected in two tasks. Auto- and cross-spectral exponents — characterizing regional fractal dynamics and FrC, respectively, — were found reduced in HE when compared to YC over most of the cortex. Additionally, fractal scaling of frontoparietal connections expressed an inverse relationship with task performance in visual memory and sustained attention domains in elderly, but not in young individuals. Our results confirm that the fractal nature of brain connectivity — as captured by MRCSA — is affected in healthy aging. Furthermore, FrC appears as a sensitive neurophysiological marker of age-related CD.

Connectome-based fingerprint of motor impairment is stable along the course of Parkinson's disease.

Functional alterations in brain connectivity have previously been described in Parkinson's disease, but it is not clear whether individual differences in connectivity profiles might be also linked to severity of motor-symptom manifestation. Here we investigated the relevance of individual functional connectivity patterns measured with resting-state fMRI with respect to motor-symptom severity in Parkinson's disease, through a whole-brain, data-driven approach (connectome-based predictive modeling). Neuroimaging and clinical data of Parkinson's disease patients from the Parkinson's Progression Markers Initiative were derived at baseline (session 1, n = 81) and at follow-up (session 2, n = 53). Connectome-based predictive modeling protocol was implemented to predict levels of motor impairment from individual connectivity profiles. The resulting predictive model comprised a network mainly involving functional connections between regions located in the cerebellum, and in the motor and frontoparietal networks. The predictive power of the model was stable along disease progression, as the connectivity within the same network could predict levels of motor impairment, even at a later stage of the disease. Finally, connectivity profiles within this network could be identified at the individual level, suggesting the presence of individual fingerprints within resting-state fMRI connectivity associated with motor manifestations in Parkinson's disease.

Subacute aphasia recovery is associated with resting-state connectivity within and beyond the language network.

To examine changes to connectivity after aphasia treatment in the first 3 months after stroke. Twenty people experiencing aphasia within the first 3 months of stroke completed MRI before and immediately following 15 hours of language treatment. They were classified based on their response to treatment on a naming test of nouns as either high responders (10% improvement or more), or low responders (<10% improvement). Groups were similar in age, gender distribution, education, days since stroke, stroke volume, and baseline severity. Resting-state functional connectivity analysis was limited to the connectivity of the left fusiform gyrus with the bilateral inferior frontal gyrus, supramarginal gyrus, angular gyrus, and superior, middle, and inferior temporal gyrus, based on previous studies showing the importance of left fusiform gyrus in naming performance. Baseline ipsilateral connectivity between the left fusiform gyrus and the language network was similar between high and low responders to therapy when controlling for stroke volume. Following therapy, change in connectivity was significantly greater among high responders between the left fusiform gyrus and the ipsilateral and contralateral pars triangularis, ipsilateral pars opercularis and superior temporal gyrus, and contralateral angular gyrus when compared with low responders. An account of these findings incorporates primarily proximal connectivity restoration, but also potentially reflects select contralateral compensatory reorganization. The latter is often associated with chronic recovery, reflecting the transitional nature of the subacute period.

Greater affective network maturity is associated with better clinical outcomes in women with early sexual trauma.

Early-life adversity accelerates the maturation of affect-related circuitry, which might be a short-term adaptation with long-term tradeoffs. Sexual trauma is associated with a particularly strong impact on pubertal development and mental health outcomes. Our objective was to test the relations between trauma type, affective network maturity, and mental health outcomes in young women with trauma history. Trauma-exposed women aged 18-29 completed a clinical interview (n = 35) and an fMRI scan (n = 28). We used a public data set to train a machine learning algorithm to predict age from resting-state affective network connectivity and calculated network maturity as the difference between predicted and true age. We also performed principal component analysis on mental health outcomes and retained two components: clinical and state psychological outcomes. Compared to nonsexual trauma (n = 17), sexual trauma (n = 11) was associated with greater affective network maturity. In addition, for sexual trauma only, greater affective network maturity was associated with better clinical but not state psychological outcomes. These results suggest that sexual trauma during development might uniquely alter the maturational trajectory of affect-related circuitry, with distinct mental health consequences in emerging adulthood. Whereas delayed affective network maturation is associated with adverse clinical outcomes, accelerated affective network maturation might confer resilience in survivors.

Effective resting-state connectivity in severe unipolar depression before and after electroconvulsive therapy

BackgroundElectroconvulsive therapy (ECT) is one of the most effective treatments for severe depressive disorders. A recent multi-center study found no consistent changes in correlation-based (undirected) resting-state connectivity after ECT. Effective (directed) connectivity may provide more insight into the working mechanism of ECT. ObjectiveWe investigated whether there are consistent changes in effective resting-state connectivity. MethodsThis multi-center study included data from 189 patients suffering from severe unipolar depression and 59 healthy control participants. Longitudinal data were available for 81 patients and 24 healthy controls. We used dynamic causal modeling for resting-state functional magnetic resonance imaging to determine effective connectivity in the default mode, salience and central executive networks before and after a course of ECT. Bayesian general linear models were used to examine differences in baseline and longitudinal effective connectivity effects associated with ECT and its effectiveness. ResultsCompared to controls, depressed patients showed many differences in effective connectivity at baseline, which varied according to the presence of psychotic features and later treatment outcome. Additionally, effective connectivity changed after ECT, which was related to ECT effectiveness. Notably, treatment effectiveness was associated with decreasing and increasing effective connectivity from the posterior default mode network to the left and right insula, respectively. No effects were found using correlation-based (undirected) connectivity. ConclusionsA beneficial response to ECT may depend on how brain regions influence each other in networks important for emotion and cognition. These findings further elucidate the working mechanisms of ECT and may provide directions for future non-invasive brain stimulation research.

Enhanced amygdala–cingulate connectivity associates with better mood in both healthy and depressive individuals after sleep deprivation

Sleep loss robustly disrupts mood and emotion regulation in healthy individuals but can have a transient antidepressant effect in a subset of patients with depression. The neural mechanisms underlying this paradoxical effect remain unclear. Previous studies suggest that the amygdala and dorsal nexus (DN) play key roles in depressive mood regulation. Here, we used functional MRI to examine associations between amygdala- and DN-related resting-state connectivity alterations and mood changes after one night of total sleep deprivation (TSD) in both healthy adults and patients with major depressive disorder using strictly controlled in-laboratory studies. Behavioral data showed that TSD increased negative mood in healthy participants but reduced depressive symptoms in 43% of patients. Imaging data showed that TSD enhanced both amygdala- and DN-related connectivity in healthy participants. Moreover, enhanced amygdala connectivity to the anterior cingulate cortex (ACC) after TSD associated with better mood in healthy participants and antidepressant effects in depressed patients. These findings support the key role of the amygdala-cingulate circuit in mood regulation in both healthy and depressed populations and suggest that rapid antidepressant treatment may target the enhancement of amygdala-ACC connectivity.

Electroencephalography-Derived Functional Connectivity in Sensorimotor Networks in Post Stroke Fatigue

BackgroundPoor suppression of anticipated sensory information from muscle contractions is thought to underlie high fatigue. Such diminished task-related sensory attenuation is reflected in resting state connectivity. Here we test the hypothesis ‘altered electroencephalography (EEG)-derived functional connectivity in somatosensory network in the beta band, is a signature of fatigue in post-stroke fatigue’.MethodsIn non-depressed, minimally impaired stroke survivors (n = 29), with median disease duration of 5 years, resting state neuronal activity was measured using 64-channel EEG. Graph theory-based network analysis measure of functional connectivity via small-world index (SW) was calculated focusing on right and left motor (Brodmann areas 4, 6, 8, 9, 24 and 32) and sensory (Brodmann areas 1, 2, 3, 5, 7, 40 and 43) networks, in the beta (13–30 Hz) frequency range. Fatigue was measured using Fatigue Severity Scale - FSS (Stroke), with scores of > 4, defined as high fatigue.ResultsResults confirmed the working hypothesis, with high fatigue stroke survivors showing higher small-worldness in the somatosensory networks when compared to low fatigue.ConclusionHigh levels of small-worldness in somatosensory networks indicates altered processing of somesthetic input. Such altered processing would explain high effort perception within the sensory attenuation model of fatigue.

Relationship between carotid intima-media thickness (cIMT) and dual-system imbalance in tobacco dependence: An rs-fMRI research.

According to the classic cognitive behavioral theory proposes, dysfunctional goal-directed and habit control systems are considered central to the pathogenesis of dependent behavior and impair recovery from addictions. The functional connectivity (FC) of the brain circuits for goal-directed or habitual behavior has not been clearly reported in tobacco-dependent groups. Smoking is one of the factors in the formation of atherosclerosis. Studies have shown that the thickness of carotid intima-media (cIMT) is associated with attention-executive-psychomotor functioning. Therefore, we hypothesized whether cIMT in tobacco-dependent individuals is associated with changes in the FC of the dual-system network. A total of 29 male tobacco-dependent subjects (tobacco-dependent group) (mean age: 64.20 years, standard deviation [SD]: 4.81 years) underwent resting-state functional magnetic resonance imaging (rs-fMRI). Exactly 28 male nonsmokers (control group) (mean age: 61.95 years, SD: 5.52 years) were also recruited to undergo rs-fMRI. We used the dorsolateral striatum (putamen) and dorsomedial striatum (caudate) as regions of interest for whole-brain resting-state connectivity to construct habitual and goal-directed brain networks, respectively. In addition, all participants were evaluated by carotid artery ultrasound to obtain the cIMT values. Then, we compared the dual-system brain networks between the tobacco dependence and control groups and the relationship between cIMT and imbalance of dual-system brain networks in tobacco dependence. The results showed a reduction in the connection between the caudate and precuneus and an increased connection between the putamen and prefrontal cortex; and supplementary motor area. The bilateral connectivity between the caudate and inferior frontal gyrus showed a significant negative correlation with the cIMT, and no positive correlation was observed with cIMT in the brain region that connects to the caudate. However, for the putamen, increased connectivity with the inferior temporal and medial frontal gyri was strongly associated with a high cIMT. The results indicate that the formation of tobacco dependence behavior is related to changes in the dual-system brain network. Carotid sclerosis is associated with the weakening of the goal-directed network and enhancement of the habit network in tobacco dependence. This finding suggests that tobacco dependence behavior and clinical vascular diseases are related to changes in brain functional networks.

Causal evidence for the processing of bodily self in the anterior precuneus

To probe the causal importance of the human posteromedial cortex (PMC) in processing the sense of self, we studied a rare cohort of nine patients with electrodes implanted bilaterally in the precuneus, posterior cingulate, and retrosplenial regions with a combination of neuroimaging, intracranial recordings, and direct cortical stimulations. In all participants, the stimulation of specific sites within the anterior precuneus (aPCu) caused dissociative changes in physical and spatial domains. Using single-pulse electrical stimulations and neuroimaging, we present effective and resting-state connectivity of aPCu hot zone with the rest of the brain and show that they are located outside the boundaries of the default mode network (DMN) but connected reciprocally with it. We propose that the function of this subregion of the PMC is integral to a range of cognitive processes that require the self's physical point of reference, given its location within a spatial environment.

Metreleptin Robustly Increases Resting-state Brain Connectivity in Treatment-naïve Female Patients With Lipodystrophy.

Research in lipodystrophy (LD) and its treatment with metreleptin has not only helped patients with LD but has opened new directions in investigating leptin's role in metabolism and the regulation of eating behavior. Previously, in a study with patients with LD undergoing metreleptin treatment using functional magnetic resonance imaging (MRI), we found significantly increased resting-state brain connectivity in 3 brain areas including the hypothalamus. In this study, we aimed to reproduce our functional MRI findings in an independent sample and compare results to healthy participants. Measurements in 4 female patients with LD undergoing metreleptin treatment and 3 healthy untreated controls were performed at 4 different time points over 12 weeks. To identify treatment-related brain connectivity alterations, eigenvector centrality was computed from resting-state functional MRI data for each patient and each session. Thereafter, analysis aimed at detecting consistent brain connectivity changes over time across all patients. In parallel to metreleptin treatment of the patients with LD, we found a significant brain connectivity increase in the hypothalamus and bilaterally in posterior cingulate gyrus. Using a 3-factorial model, a significant interaction between group and time was found in the hypothalamus. Investigating brain connectivity alterations with metreleptin treatment using an independent sample of patients with LD, we have reproduced an increase of brain connectivity in hedonic and homeostatic central nervous networks observed previously with metreleptin treatment. These results are an important contribution to ascertain brain leptin action and help build a foundation for further research of central nervous effects of this important metabolic hormone.

Resting-State Connectivity Changes After Goal-Oriented Attentional Self-Regulation Training in Veterans With Mild Traumatic Brain Injury: Preliminary Findings from a Randomized Controlled Trial.

Mild traumatic brain injury (mTBI) can have lasting consequences on cognitive functioning and well-being. Goal-Oriented Attentional Self-Regulation (GOALS) training has been shown to improve attention and executive functioning, as well as emotional functioning, in veterans with chronic TBI. An ongoing clinical trial (NCT02920788) is further evaluating GOALS training, including underlying neural mechanisms of change. The present study aimed to examine training-induced neuroplasticity by resting-state functional connectivity (rsFC) changes in GOALS versus active control. Veterans with a history of mTBI ≥6 months post-injury (N = 33) were randomly assigned to GOALS (n = 19) or an intensity-matched active control group (Brain Health Education [BHE] training; n = 14). GOALS consists of attention regulation and problem solving applied to individually defined, relevant goals through a combination of group, individual, and home practice sessions. Participants underwent multi-band resting-state functional magnetic resonance imaging at baseline and post-intervention. Exploratory 2 × 2 mixed analyses of variance identified pre-to-post changes in seed-based connectivity for GOALS versus BHE in five significant clusters. GOALS versus BHE demonstrated a significant increase in right lateral pre-frontal cortex connectivity with the right frontal pole and right middle temporal gyrus, as well as increased posterior cingulate connectivity with the pre-central gyrus. Rostral pre-frontal cortex connectivity with the right precuneus and the right frontal pole decreased in GOALS versus BHE. These GOALS-related changes in rsFC point to potential neural mechanisms underlying the intervention. This training-induced neuroplasticity may play a role in improved cognitive and emotional functioning post-GOALS.

Early Family Intervention for Youth at Risk for Bipolar Disorder: Psychosocial and Neural Mediators of Outcome.

The impairing neurodevelopmental course of bipolar disorder (BD) suggests the importance of early intervention for youth in the beginning phases of the illness. We report the results of a 3-site randomized trial of family-focused therapy for youth at high-risk (FFT-HR) for BD, and explore psychosocial and neuroimaging variables as mediators of treatment effects. High-risk youth (<18 years) with major depressive disorder or other specified BD, active mood symptoms, and a family history of BD were randomly assigned to 4 months of FFT-HR (psychoeducation, communication and problem-solving skills training) or 4 months of enhanced care psychoeducation. Adjunctive pharmacotherapy was provided by study psychiatrists. Neuroimaging scans were conducted before and after psychosocial treatments in eligible participants. Independent evaluators interviewed participants every 4-6 months over 1-4 years regarding symptomatic outcomes. Among 127 youth (mean 13.2 ± 2.6 years) over a median of 98 weeks, FFT-HR was associated with longer intervals prior to new mood episodes and lower levels of suicidal ideation than enhanced care. Reductions in perceived family conflict mediated the effects of psychosocial interventions on the course of mood symptoms. Among 34 participants with pre-/post-treatment fMRI scans, youth in FFT-HR had (a) stronger resting state connectivity between ventrolateral PFC and anterior default mode network, and (b) increased activity of dorsolateral and medial PFC in emotion processing and problem-solving tasks, compared to youth in enhanced care. FFT-HR may delay new mood episodes in symptomatic youth with familial liability to BD. Putative treatment mechanisms include neural adaptations suggestive of improved emotion regulation.

Sex differences in resting-state functional networks in awake rats.

Sex-related differences can be found in many brain disorders and psychophysiological traits, highlighting the importance to systematically understand the sex differences in brain function in humans and animal models. Despite emerging effort to address sex differences in behaviors and disease models in rodents, how brain-wide functional connectivity (FC) patterns differ between male and female rats remains largely unknown. Here, we used resting-state functional magnetic resonance imaging (rsfMRI) to investigate regional and systems-level differences between female and male rats. Our data show that female rats display stronger hypothalamus connectivity, whereas male rats exhibit more prominent striatum-related connectivity. At the global scale, female rats demonstrate stronger segregation within the cortical and subcortical systems, while male rats display more prominent cortico-subcortical interactions, particularly between the cortex and striatum. Taken together, these data provide a comprehensive framework of sex differences in resting-state connectivity patterns in the awake rat brain, and offer a reference for studies aiming to reveal sex-related FC differences in different animal models of brain disorders.

Predicting Alcohol-Related Memory Problems in Older Adults: A Machine Learning Study with Multi-Domain Features.

Memory problems are common among older adults with a history of alcohol use disorder (AUD). Employing a machine learning framework, the current study investigates the use of multi-domain features to classify individuals with and without alcohol-induced memory problems. A group of 94 individuals (ages 50-81 years) with alcohol-induced memory problems (the memory group) were compared with a matched control group who did not have memory problems. The random forests model identified specific features from each domain that contributed to the classification of the memory group vs. the control group (AUC = 88.29%). Specifically, individuals from the memory group manifested a predominant pattern of hyperconnectivity across the default mode network regions except for some connections involving the anterior cingulate cortex, which were predominantly hypoconnected. Other significant contributing features were: (i) polygenic risk scores for AUD, (ii) alcohol consumption and related health consequences during the past five years, such as health problems, past negative experiences, withdrawal symptoms, and the largest number of drinks in a day during the past twelve months, and (iii) elevated neuroticism and increased harm avoidance, and fewer positive "uplift" life events. At the neural systems level, hyperconnectivity across the default mode network regions, including the connections across the hippocampal hub regions, in individuals with memory problems may indicate dysregulation in neural information processing. Overall, the study outlines the importance of utilizing multidomain features, consisting of resting-state brain connectivity data collected ~18 years ago, together with personality, life experiences, polygenic risk, and alcohol consumption and related consequences, to predict the alcohol-related memory problems that arise in later life.

Paediatric obesity and metabolic syndrome associations with cognition and the brain in youth: Current evidence and future directions.

Obesity and components of the metabolic syndrome (MetS) are associated with differences in brain structure and function and in general and food-related cognition in adults. Here, we review evidence for similar phenomena in children and adolescents, with a focus on the implications of extant research for possible underlying mechanisms and potential interventions for obesity and MetS in youth. Current evidence is limited by a relative reliance on small cross-sectional studies. However, we find that youth with obesity and MetS or MetS components show differences in brain structure, including alterations in grey matter volume and cortical thickness across brain regions subserving reward, cognitive control and other functions, as well as in white matter integrity and volume. Children with obesity and MetS components also show some evidence for hyperresponsivity of food reward regions and hyporesponsivity of cognitive control circuits during food-related tasks, altered brain responses to food tastes, and altered resting-state connectivity including between cognitive control and reward processing networks. Potential mechanisms for these findings include neuroinflammation, impaired vascular reactivity, and effects of diet and obesity on myelination and dopamine function. Future observational research using longitudinal measures, improved sampling strategies and study designs, and rigorous statistical methods, promises to further illuminate dynamic relationships and causal mechanisms. Intervention studies targeted at modifiable biological and behavioural factors associated with paediatric obesity and MetS can further inform mechanisms, as well as test whether brain and behaviour can be altered for beneficial outcomes.

Resting state connectivity in people living with HIV before and after stopping heavy drinking.

Heavy alcohol use in people living with HIV (PLWH) has widespread negative effects on neural functioning. It remains unclear whether experimentally-induced reduction in alcohol use could reverse these effects. We sought to determine the effects of 30-days drinking cessation/reduction on resting state functional connectivity in people with and without HIV. Thirty-five participants (48.6% PLWH) demonstrating heavy alcohol use attempted to stop drinking for 30 days via contingency management (CM). MRI was acquired at baseline and after thirty days, and functional connectivity across five resting-state fMRI (rsfMRI) networks was calculated with the Conn toolbox for Matlab and examined in relation to transdermal alcohol concentration (TAC) recorded by the ankle-worn secure continuous remote alcohol monitor (SCRAM) and self-reported alcohol use (timeline follow-back; TLFB). Associations between alcohol use and reduction, HIV status, functional connectivity, and change in functional connectivity across five major rsfMRI networks were determined relative to the pre- and post-CM timepoints. Baseline resting-state functional connectivity was not significantly associated with average TAC-AUC during the pre-CM period, though higher self-reported alcohol use over the preceding 30 days was significantly associated with higher baseline connectivity within the Dorsal Attention Network (DAN; p-FDR < 0.05). Baseline connectivity within the Salience network was significantly negatively related to objective drinking reduction after intervention (DAN; p-FDR < 0.05), whereas baseline connectivity within the Limbic network was positively associated with self-reported drinking reduction (p-FDR < 0.05). Change in between-networks functional connectivity after intervention was significantly positively associated with biosensor-confirmed drinking reduction such that higher reduction was associated with stronger connectivity between the limbic and fronto-parietal control networks (p-FDR < 0.05). PLWH with lower DAN connectivity at baseline demonstrated poorer alcohol reduction than those with higher DAN connectivity at baseline. Lower resting-state functional connectivity of the Salience network significantly predicted stronger drinking reduction across all participants, suggesting a potential biomarker for reduced susceptibility to the environmental and social cues that often make alcohol use reduction attempts unsuccessful. Increased between-networks connectivity was observed in participants with higher alcohol reduction after CM, suggesting a positive benefit to brain connectivity associated with reduced drinking. PLWH with lower baseline DAN connectivity may not benefit as greatly from CM for alcohol reduction.

Improved brain stimulation targeting by optimising image acquisition parameters

Functional connectivity analysis from rs-fMRI data has been used for determining cortical targets in therapeutic applications of non-invasive brain stimulation using transcranial magnetic stimulation (TMS). Reliable connectivity measures are therefore essential for every rs-fMRI-based TMS targeting approach. Here, we examine the effect of echo time (TE) on the reproducibility and spatial variability of resting-state connectivity measures. We acquired multiple runs of single-echo fMRI data with either short (TE = 30 ms) or long (TE = 38 ms) echo time to investigate inter-run spatial reproducibility of a clinically relevant functional connectivity map, i.e., originating from the sgACC. We find that connectivity maps obtained from TE = 38 ms rs-fMRI data are significantly more reliable than those obtained from TE = 30 ms data sets. Our results clearly show that optimizing sequence parameters can be beneficial for ensuring high-reliability resting-state acquisition protocols to be used for TMS targeting. The differences between reliability in connectivity measures for different TEs could inform future clinical research in optimising MR sequences.

Resting-State Connectivity in Acute and Subacute Poststroke Aphasia: A Functional Near-Infrared Spectroscopy Pilot Study.

Background: Understanding how brain function and language skills change during early (acute and subacute) stroke phases is critical for maximizing patient recovery, yet functional neuroimaging studies of early aphasia are scarce. In this pilot study, we used functional near-infrared spectroscopy (fNIRS) to investigate how resting-state functional connectivity (rs-FC) in early aphasia differs from neurologically healthy adults and is related to language deficits. Materials and Methods: Twenty individuals with aphasia (12 acute and 8 subacute phase) and 15 healthy controls underwent rs-fNIRS imaging with a 46-channel montage centered over bilateral perisylvian language areas. FC was computed using a prewhitening, autoregressive Pearson correlation routine applied to preprocessed oxyhemoglobin (HbO) data. Connections were classified as left intra-, right intra-, or interhemispheric. We then compared rs-FC between groups by connection type and examined Spearman correlations between rs-FC averages and language measures within patients. Results: Participants in the acute phase had significantly reduced global rs-FC across all HbO-based connections compared to healthy controls. No significant differences were found in rs-FC between controls and patients in the subacute phase. Controlling for days since stroke, stronger right intra- and interhemispheric rs-FC was related to milder aphasia across all patients. Exploratory correlations revealed that relationships between language measures and rs-FC differed between acute and subacute patient groups. Conclusion: This study provides preliminary evidence that fNIRS-based rs-FC measures may be a viable metric to index the early impacts of stroke in people with aphasia.