Supplemental material, sj-pdf-1-msj-10.1177_13524585211018116 for Altered anterior default mode network dynamics in progressive multiple sclerosis by Giulia Bommarito, Anjali Tarun, Younes Farouj, Maria Giulia Preti, Maria Petracca, Amgad... more
Supplemental material, sj-pdf-1-msj-10.1177_13524585211018116 for Altered anterior default mode network dynamics in progressive multiple sclerosis by Giulia Bommarito, Anjali Tarun, Younes Farouj, Maria Giulia Preti, Maria Petracca, Amgad Droby, Mohamed Mounir El Mendili, Matilde Inglese and Dimitri Van De Ville in Multiple Sclerosis Journal
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Patterns of human brain activity emerge from temporally limited fMRI observations, allowing identification of individuals.
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Brain signatures of functional activity have shown promising results in both decoding brain states, meaning distinguishing between different tasks, and fingerprinting, that is identifying individuals within a large group. Importantly,... more
Brain signatures of functional activity have shown promising results in both decoding brain states, meaning distinguishing between different tasks, and fingerprinting, that is identifying individuals within a large group. Importantly, these brain signatures do not account for the underlying brain anatomy on which brain function takes place. Structure-function coupling based on graph signal processing (GSP) has recently revealed a meaningful spatial gradient from unimodal to transmodal regions, on average in healthy subjects during resting-state. Here, we explore the potential of GSP to introduce new imaging-based biomarkers to characterize tasks and individuals. We used multimodal magnetic resonance imaging of 100 unrelated healthy subjects from the Human Connectome Project both during rest and seven different tasks and adopted a support vector machine classification approach for both decoding and fingerprinting, with various cross-validation settings. We found that structurefunctio...
Physiological evidence suggests that neighboring brain regions have similar perfusion characteristics (vascular supply, collateral blood flow). It is largely unknown whether integrating perfusion CT (pCT) information from the area... more
Physiological evidence suggests that neighboring brain regions have similar perfusion characteristics (vascular supply, collateral blood flow). It is largely unknown whether integrating perfusion CT (pCT) information from the area surrounding a given voxel (i.e. the receptive field (RF)) improves the prediction of infarction of this voxel. Based on general linear regression models (GLMs) and using acute pCT-derived maps, we compared the added value of cuboid RF to predict the final infarct. To this aim, we included 144 stroke patients with acute pCT and follow-up MRI, used to delineate the final infarct. Overall, the performance of GLMs to predict the final infarct improved when using RF for all pCT maps (cerebral blood flow, cerebral blood volume, mean transit time and time-to-maximum of the tissue residual function (Tmax)). The highest performance was obtained with Tmax (glm(Tmax); AUC = 0.89 ± 0.03 with RF vs. 0.78 ± 0.02 without RF; p
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Research Interests: Computer Science and IEEE
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Graph spectral analysis can yield meaningful embeddings of graphs by providing insight into distributed features not directly accessible in nodal domain. Recent efforts in graph signal processing have proposed new decompositions—for... more
Graph spectral analysis can yield meaningful embeddings of graphs by providing insight into distributed features not directly accessible in nodal domain. Recent efforts in graph signal processing have proposed new decompositions—for example, based on wavelets and Slepians—that can be applied to filter signals defined on the graph. In this work, we take inspiration from these constructions to define a new guided spectral embedding that combines maximizing energy concentration with minimizing modified embedded distance for a given importance weighting of the nodes. We show that these optimization goals are intrinsically opposite, leading to a well-defined and stable spectral decomposition. The importance weighting allows us to put the focus on particular nodes and tune the trade-off between global and local effects. Following the derivation of our new optimization criterion, we exemplify the methodology on the C. elegans structural connectome. The results of our analyses confirm known...
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The incidence of Alzheimer's disease (AD) strongly relates to advanced age and progressive deposition of cerebral amyloid-beta (Aβ), hyperphosphorylated tau, and iron. The purpose of this study was to investigate the relationship... more
The incidence of Alzheimer's disease (AD) strongly relates to advanced age and progressive deposition of cerebral amyloid-beta (Aβ), hyperphosphorylated tau, and iron. The purpose of this study was to investigate the relationship between cerebral dynamic functional connectivity and variability of long-term cognitive performance in healthy, elderly subjects, allowing for local pathology and genetic risk. Thirty seven participants (mean (SD) age 74 (6.0) years, Mini-Mental State Examination 29.0 (1.2)) were dichotomized based on repeated neuropsychological test performance within 2 years. Cerebral Aβ was measured by (11)C Pittsburgh Compound-B positron emission tomography, and iron by quantitative susceptibility mapping magnetic resonance imaging (MRI) at an ultra-high field strength of 7 Tesla (7T). Dynamic functional connectivity patterns were investigated by resting-state functional MRI at 7T and tested for interactive effects with genetic AD risk (apolipoprotein E (ApoE)-ε4 ca...
Research Interests: Magnetic Resonance Imaging, Positron Emission Tomography, Memory, Brain, Humans, and 14 moreFemale, Disease, Male, Follow-up studies, Apolipoprotein E, Aged, Middle Aged, Rest, Radiopharmaceuticals, Thiazoles, Alzheimer Disease, aniline Compounds, Neuropsychological Tests, and Medical and Health Sciences
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The fetal origin of the posterior cerebral artery (fPCA) is a frequent vascular variant in 11-29% of the population. For the fPCA, blood flow in the PCA originates from the anterior instead of the posterior circulation. We tested whether... more
The fetal origin of the posterior cerebral artery (fPCA) is a frequent vascular variant in 11-29% of the population. For the fPCA, blood flow in the PCA originates from the anterior instead of the posterior circulation. We tested whether this blood supply variant impacts the cerebral blood flow assessed by arterial spin labeling (ASL), cerebrovascular reserve as well as resting-state static functional connectivity (sFC) in the sense of a systematic confound. The study included 385 healthy, elderly subjects (mean age: 74.18 years [range: 68.9-90.4]; 243 female). Participants were classified into normal vascular supply (n = 296, 76.88%), right fetal origin (n = 23, 5.97%), left fetal origin (n = 16, 4.16%), bilateral fetal origin (n = 4, 1.04%), and intermediate (n = 46, 11.95%, excluded from further analysis) groups. ASL-derived relative cerebral blood flow (relCBF) maps and cerebrovascular reserve (CVR) maps derived from a CO2 challenge with blocks of 7% CO2 were compared. Additiona...
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Research Interests: Psychology, Magnetic Resonance Imaging, Addiction (Biology), Medicine, Prospective studies, and 15 moreHumans, Smoking, Cerebral Cortex, Insula, Female, Male, Craving, Adult, Analysis of Variance, Video Recording, Brain Diseases, Anterior cingulate cortex, Cingulate cortex, Psychology and Cognitive Sciences, and Medical and Health Sciences
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The tractographic reconstruction of anatomical and microstructural features provided by Magnetic Resonance (MR) Diffusion Tensor Imaging (DTI) gives essential information of brain damage in several pathological animal models. The... more
The tractographic reconstruction of anatomical and microstructural features provided by Magnetic Resonance (MR) Diffusion Tensor Imaging (DTI) gives essential information of brain damage in several pathological animal models. The optimization of a tractographic protocol is undertaken in normal rats for the future construction of a reference atlas, as prerequisite for preclinical pathological in-vivo studies. High field, preclinical in-vivo DTI faces important difficulties relevant to Signal-to-Noise Ratio (SNR), distortion, high required resolution, movement sensitivity. Given a pixel-size of 0.17 mm and TE/TR = 29/6500 ms, b value and slice thickness were fixed at 700 s/mm(2) and 0.58 mm, respectively, on preventive ex-vivo studies. In-vivo studies led to the choice of 30 diffusion directions, averaged on 16 runs. The final protocol required 51 min scanning and permitted a reliable reconstruction of main rat brain bundles. Tract reconstruction stopping rules required proper setting. In conclusion, the viability of DTI tractography on in-vivo rat studies was shown, towards the construction of a normal reference atlas.
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Research Interests: Demography, Developmental Biology, Image Processing, Computational Biology, Computational Neuroscience, and 15 moreMagnetic Resonance Imaging, Diffusion Tensor Imaging, Cognitive Neuroscience, Brain Mapping, Anatomy, Brain, Humans, Female, Male, Aged, Adult, Disease Progression, Diagnostic Radiology, Alzheimer Disease, and Case Control Studies
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Background. The growing social emergency represented by Alzheimer’s disease (AD) and the lack of medical treatments able to modify the disease course have kindled the interest in nonpharmacological therapies. Objective. We introduced a... more
Background. The growing social emergency represented by Alzheimer’s disease (AD) and the lack of medical treatments able to modify the disease course have kindled the interest in nonpharmacological therapies. Objective. We introduced a novel nonpharmacological approach for people with AD (PWA) named Multidimensional Stimulation group Therapy (MST) to improve PWA condition in different disease domains: cognition, behavior, and motor functioning. Methods. Enrolling 60 PWA in a mild to moderate stage of the disease, we evaluated the efficacy of MST with a randomized-controlled study. Neuropsychological and neurobehavioral measures and functional magnetic resonance imaging (fMRI) data were considered as outcome measures. Results. The following significant intervention-related changes were observed: reduction in Neuropsychiatric Inventory scale score, improvement in language and memory subscales of Alzheimer’s Disease Assessment Scale–Cognitive subscale, and increased fMRI activations in...
Research Interests: Cognitive Science, Magnetic Resonance Imaging, Treatment Outcome, Group Psychotherapy, Brain, and 15 moreHumans, Female, Male, Regression Analysis, Caregivers, Clinical Sciences, Aged, Oxygen, Time Factors, Alzheimer Disease, Neurosciences, Cognition disorders, Case Control Studies, Neuropsychological Tests, and Residence Characteristics
Alterations in activity and connectivity of brain circuits implicated in emotion processing and emotion regulation have been observed during resting-state for different clinical phases of bipolar disorders (BD), but longitudinal... more
Alterations in activity and connectivity of brain circuits implicated in emotion processing and emotion regulation have been observed during resting-state for different clinical phases of bipolar disorders (BD), but longitudinal investigations across different mood states in the same patients are still rare. Furthermore, measuring dynamics of functional connectivity patterns offers a powerful method to explore changes in the brain’s intrinsic functional organization across mood states. We used a novel co-activation pattern (CAP) analysis to explore the dynamics of amygdala connectivity at rest in a cohort of 20 BD patients prospectively followed-up and scanned across distinct mood states: euthymia (20 patients; 39 sessions), depression (12 patients; 18 sessions), or mania/hypomania (14 patients; 18 sessions). We compared them to 41 healthy controls scanned once or twice (55 sessions). We characterized temporal aspects of dynamic fluctuations in amygdala connectivity over the whole b...
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The brain is an assembly of neuronal populations interconnected by structural pathways. Brain activity is expressed on and constrained by this substrate. Therefore, statistical dependencies between functional signals in directly connected... more
The brain is an assembly of neuronal populations interconnected by structural pathways. Brain activity is expressed on and constrained by this substrate. Therefore, statistical dependencies between functional signals in directly connected areas can be expected higher. However, the degree to which brain function is bound by the underlying wiring diagram remains a complex question that has been only partially answered. Here, we introduce the structural-decoupling index to quantify the coupling strength between structure and function, and we reveal a macroscale gradient from brain regions more strongly coupled, to regions more strongly decoupled, than expected by realistic surrogate data. This gradient spans behavioral domains from lower-level sensory function to high-level cognitive ones and shows for the first time that the strength of structure-function coupling is spatially varying in line with evidence derived from other modalities, such as functional connectivity, gene expression...