References of "Salmon, Eric"
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See detailBrain metabolic dysfunction in Capgras syndrome during Alzheimer’s disease: a positron emission tomography study
Jedidi, Haroun ULg; Daury, Noémy; Cappa, Rémi et al

Poster (2013, June)

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See detailPreclinical radiation dosimetry for the novel SV2A radiotracer [18F]UCB-H
Bretin, Florian ULg; Warnock, Geoffrey; Bahri, Mohamed Ali ULg et al

in European Journal of Nuclear Medicine and Molecular Imaging Research (2013), 3(1), 35

Background: [18F]UCB-H was developed as a novel radiotracer with a high affinity for synaptic vesicle protein 2A, the binding site for the antiepileptic levetiracetam. The objectives of this study were to ... [more ▼]

Background: [18F]UCB-H was developed as a novel radiotracer with a high affinity for synaptic vesicle protein 2A, the binding site for the antiepileptic levetiracetam. The objectives of this study were to evaluate the radiation dosimetry of [18F]UCB-H in a preclinical trial and to determine the maximum injectable dose according to guidelines for human biomedical research. The radiation dosimetry was derived by organ harvesting and dynamic micro positron emission tomography (PET) imaging in mice, and the results of both methods were compared. Methods: Twenty-four male C57BL-6 mice were injected with 6.96 ± 0.81 MBq of [18F]UCB-H, and the biodistribution was determined by organ harvesting at 2, 5, 10, 30, 60, and 120 min (n = 4 for each time point). Dynamic microPET imaging was performed on five male C57BL-6 mice after the injection of 9.19 ± 3.40 MBq of [18F]UCB-H. A theoretical dynamic bladder model was applied to simulate urinary excretion. Human radiation dose estimates were derived from animal data using the International Commission on Radiological Protection 103 tissue weighting factors. Results: Based on organ harvesting, the urinary bladder wall, liver and brain received the highest radiation dose with a resulting effective dose of 1.88E-02 mSv/MBq. Based on dynamic imaging an effective dose of 1.86E-02 mSv/MBq was calculated, with the urinary bladder wall and liver (brain was not in the imaging field of view) receiving the highest radiation. Conclusions: This first preclinical dosimetry study of [18F]UCB-H showed that the tracer meets the standard criteria for radiation exposure in clinical studies. The dose-limiting organ based on US Food and Drug Administration (FDA) and European guidelines was the urinary bladder wall for FDA and the effective dose for Europe with a maximum injectable single dose of approximately 325 MBq was calculated. Although microPET imaging showed significant deviations from organ harvesting, the Pearson’s correlation coefficient between radiation dosimetry derived by either method was 0.9666. [less ▲]

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See detailRadiosynthesis and first small animal microPET imaging of [18F]UCB-H, a new fluorine-18 labelled tracer targeting synaptic vesicle protein 2A (SV2A)
Aerts, Joël ULg; Otabashi, Muhamed; Giacomelli, Fabrice ULg et al

Conference (2013)

Aim. We report the radiosynthesis and first rat microPET imaging of a new fluorine-18 tracer targeting the synaptic vesicle protein 2A, SV2A, identified as the binding site of the antiepileptic drug ... [more ▼]

Aim. We report the radiosynthesis and first rat microPET imaging of a new fluorine-18 tracer targeting the synaptic vesicle protein 2A, SV2A, identified as the binding site of the antiepileptic drug levetiracetam. Materials and Method. Two different nucleophilic radiosynthesis pathways were tested to obtain [18F]UCB-H, a no-carrier-added tracer in the 2-[18F]fluoropyridine family. The methods were automated on FastLab™ synthesizers. PET studies in rodents were carried out using male SD rats, imaged under isoflurane anaesthesia in a Siemens Concorde Focus 120 microPET scanner. Arterial input function was measured using an arteriovenous shunt method and beta microprobe system. All animal protocols were reviewed and accepted by animal ethical committees. Results and conclusion. A radiosynthesis yield of 30% was obtained (uncorrected for decay, 150 minutes of synthesis). Analytical methods were developed and validated to demonstrate that the quality of the tracer solution was compatible with in vivo injection. After intravenous injection, the tracer rapidly entered the brain, followed by rapid washout. PET imaging revealed high uptake of the tracer in the brain and spinal cord, matching the expected SV2A homogeneous distribution. Results indicate that [18F]UCB-H is suitable to quantify SV2A proteins in vivo and to estimate target occupancy of drugs targeting SV2A. Acknowledgments. The authors thank UCB Pharma SA Belgium for collaboration and the Walloon Region Belgium and the FRNS Belgium for financial support. [less ▲]

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See detailDifferential effects of aging on the neural correlates of recollection and familiarity
Angel, Lucie; Bastin, Christine ULg; Genon, Sarah ULg et al

in Cortex : A Journal Devoted to the Study of the Nervous System & Behavior (2013), 49

The present experiment aimed to investigate age differences in the neural correlates of familiarity and recollection, while keeping performance similar across age groups by varying task difficulty. Twenty ... [more ▼]

The present experiment aimed to investigate age differences in the neural correlates of familiarity and recollection, while keeping performance similar across age groups by varying task difficulty. Twenty young and twenty older adults performed an episodic memory task in an event-related fMRI design. At encoding, participants were presented with pictures, either once or twice. Then, they performed a recognition task, with a Remember/Know paradigm. A similar performance was observed for the two groups in the Easy condition for recollection and in the Hard condition for familiarity. Imaging data revealed the classic recollection-related and familiarity-related networks, common to young and older groups. In addition, we observed that some activity related to recollection (left frontal, left temporal, left parietal cortices and left parahippocampus) and familiarity (bilateral anterior cingulate, right frontal gyrus and left superior temporal gyrus) was reduced in older compared to young adults. However, for recollection processes only, older adults additionally recruited the right precuneus, possibly to successfully compensate for their difficulties, as suggested by a positive correlation between recollection and precuneus activity. [less ▲]

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See detailMulticlass classification of FDG PET scans for the distinction between Parkinson's disease and atypical parkinsonian syndromes
Garraux, Gaëtan ULg; Phillips, Christophe ULg; Schrouff, Jessica ULg et al

in NeuroImage: Clinical (2013), 2

Most available pattern recognition methods in neuroimaging address binary classification problems. Here, we used relevance vector machine (RVM) in combination with booststrap resampling (‘bagging’) for ... [more ▼]

Most available pattern recognition methods in neuroimaging address binary classification problems. Here, we used relevance vector machine (RVM) in combination with booststrap resampling (‘bagging’) for non-hierarchical multiclass classification. The method was tested on 120 cerebral 18fluorodeoxyglucose (FDG) positron emission tomography (PET) scans performed in patients who exhibited parkinsonian clinical features for 3.5 years on average but that were outside the prevailing perception for Parkinson's disease (PD). A radiological diagnosis of PD was suggested for 30 patients at the time of PET imaging. However, at follow-up several years after PET imaging, 42 of them finally received a clinical diagnosis of PD. The remaining 78 APS patients were diagnosed with multiple system atrophy (MSA, N = 31), progressive supranuclear palsy (PSP, N = 26) and corticobasal syndrome (CBS, N = 21), respectively. With respect to this standard of truth, classification sensitivity, specificity, positive and negative predictive values for PD were 93% 83% 75% and 96%, respectively using binary RVM (PD vs. APS) and 90%, 87%, 79% and 94%, respectively, using multiclass RVM (PD vs. MSA vs. PSP vs. CBS). Multiclass RVM achieved 45%, 55% and 62% classification accuracy for, MSA, PSP and CBS, respectively. Finally, a majority confidence ratio was computed for each scan on the basis of class pairs that were the most frequently assigned by RVM. Altogether, the results suggest that automatic multiclass RVM classification of FDG PET scans achieves adequate performance for the early differentiation between PD and APS on the basis of cerebral FDG uptake patterns when the clinical diagnosis is felt uncertain. This approach cannot be recommended yet as an aid for distinction between the three APS classes under consideration. [less ▲]

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See detailThe Importance of Encoding-Related Neural Dynamics in the Prediction of Inter-Individual Differences in Verbal Working Memory Performance
Majerus, Steve ULg; Salmon, Eric ULg; Attout, Lucie ULg

in PLoS ONE (2013), 8(7),

Studies of brain-behaviour interactions in the field of working memory (WM) have associated WM success with activation of a fronto-parietal network during the maintenance stage, and this mainly for visuo ... [more ▼]

Studies of brain-behaviour interactions in the field of working memory (WM) have associated WM success with activation of a fronto-parietal network during the maintenance stage, and this mainly for visuo-spatial WM. Using an inter-individual differences approach, we demonstrate here the equal importance of neural dynamics during the encoding stage, and this in the context of verbal WM tasks which are characterized by encoding phases of long duration and sustained attentional demands. Participants encoded and maintained 5-word lists, half of them containing an unexpected word intended to disturb WM encoding and associated task-related attention processes. We observed that inter-individual differences in WM performance for lists containing disturbing stimuli were related to activation levels in a region previously associated with task-related attentional processing, the left intraparietal sulcus (IPS), and this during stimulus encoding but not maintenance; functional connectivity strength between the left IPS and lateral prefrontal cortex (PFC) further predicted WM performance. This study highlights the critical role, during WM encoding, of neural substrates involved in task-related attentional processes for predicting inter-individual differences in verbal WM performance, and, more generally, provides support for attention-based models of WM. © 2013 Majerus et al. [less ▲]

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See detailClassification of MCI and AD patients combining PET data and psychological scores
Segovia-Román, Fermín ULg; Bastin, Christine ULg; Salmon, Eric ULg et al

in International Workshop on Advances in Regularization, Optimization, Kernel Methods and Support Vector Machines: theory and applications (2013)

This study’s aim was to measure the advantages of using psychological test data in the automatic classification of functional brain images in order to assist the diagnosis of neurodegenerative disorders ... [more ▼]

This study’s aim was to measure the advantages of using psychological test data in the automatic classification of functional brain images in order to assist the diagnosis of neurodegenerative disorders such as Alzheimer’s disease (AD). Several computer-aided diagnosis systems for AD based on PET images were developed. Some of them used psychological scores beside the image data in the classification step and others did not. The results show the ones that take into account the psychological scores achieve higher accuracy rates. [less ▲]

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See detailAutomatic differentiation between Alzheimer’s Disease and Mild Cognitive Impairment combining PET data and psychological scores
Segovia-Román, Fermín ULg; Bastin, Christine ULg; Salmon, Eric ULg et al

in 3rd International Workshop on Pattern Recognition in Neuroimaging (2013)

In recent years, several approaches to develop computer aided diagnosis systems for dementia have been pro- posed. The purpose of this work is to measure the advantages of using not only brain images as ... [more ▼]

In recent years, several approaches to develop computer aided diagnosis systems for dementia have been pro- posed. The purpose of this work is to measure the advantages of using not only brain images as data source for those systems but also some psychological scores. To this aim, we compared the accuracy rates achieved by systems that use psychological scores beside the image data in the classification step and systems that use only the image data. The experiments show that the formers achieve higher accuracy rates regardless of the procedure carried out to analyze the image data. [less ▲]

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See detailMetabolic and structural connectivity within the default mode network relates to working memory performance in young healthy adults
Yakushev, Igor; Chételat, Gael; Fischer F.U. et al

in NeuroImage (2013), 79

Studies of functional connectivity suggest that the default mode network (DMN) might be relevant for cognitive functions. Here, we examined metabolic and structural connectivity between major DMN nodes ... [more ▼]

Studies of functional connectivity suggest that the default mode network (DMN) might be relevant for cognitive functions. Here, we examined metabolic and structural connectivity between major DMN nodes, the posterior cingulate (PCC) and medial prefrontal cortex (MPFC), in relation to normal working memory (WM). DMN was captured using independent component analysis of [18F]fluorodeoxyglucose positron emission tomography (FDG-PET) data from 35 young healthy adults (27.1±5.1 years). Metabolic connectivity, a correlation between FDG uptake in PCC and MPFC, was examined in groups of subjects with (relative to median) low (n=18) and high (n=17) performance on digit span backward test as an index of verbal WM. In addition, fiber tractography based on PCC and MPFC nodes as way points was performed in a subset of subjects. FDG uptake in the DMN nodes did not differ between high and low performers. However, significantly (p=0.01) lower metabolic connectivity was found in the group of low performers. Furthermore, as compared to high performers, low performers showed lower density of the left superior cingulate bundle. Verbal WM performance is related to metabolic and structural connectivity within the DMN in young healthy adults. Metabolic connectivity as quantified with FDG-PET might be a sensitive marker of the normal variability in some cognitive functions. [less ▲]

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See detailRelationships between brain metabolism decrease in normal aging and changes in structural and functional connectivity
Chételat, Gael; Landeau, Brigitte; Salmon, Eric ULg et al

in NeuroImage (2013), 76

Normal aging is characterized by brain glucose metabolism decline predominantly in the prefrontal cortex. The goal of the present study was to assess whether this change was associated with age-related ... [more ▼]

Normal aging is characterized by brain glucose metabolism decline predominantly in the prefrontal cortex. The goal of the present study was to assess whether this change was associated with age-related alteration of white matter (WM) structural integrity and/or functional connectivity. FDG-PET data from 40 young and 57 elderly healthy participants from two research centres (n=49/48 in Centre 1/2) were analyzed. WM volume from T1-weighted MRI (Centre 1), fractional anisotropy from diffusion-tensor imaging (Centre 2), and resting-state fMRI data (Centre 1) were also obtained. Group comparisons were performed within each imaging modality. Then, positive correlations were assessed, within the elderly, between metabolism in the most affected region and the other neuroimaging modalities. Metabolism decline in the elderly predominated in the left inferior frontal junction (LIFJ). LIFJ hypometabolism was significantly associated with macrostructural and microstructural WM disturbances in long association fronto-temporo-occipital fibers, while no relationship was found with functional connectivity. The findings offer new perspectives to understand normal aging processes and open avenues for future studies to explore causality between age-related metabolism and connectivity changes. [less ▲]

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See detailImpairments of 3D visual perception in posterior cortical atrophy: functional and anatomical characterization
Gillebert, Céline; Bastin, Christine ULg; Sunaert, Stefan et al

Conference (2013)

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See detailEpisodic autobiographical memory in amnestic Mild Cognitive Impairment: What are the neural correlates?
Bastin, Christine ULg; Feyers, Dorothée ULg; Jedidi, Haroun ULg et al

in Human Brain Mapping (2013), 34

Autobiographical memory in amnestic Mild Cognitive Impairment (aMCI) is characterized by impaired retrieval of episodic memories, but relatively preserved personal semantic knowledge. This study aimed to ... [more ▼]

Autobiographical memory in amnestic Mild Cognitive Impairment (aMCI) is characterized by impaired retrieval of episodic memories, but relatively preserved personal semantic knowledge. This study aimed to identify (via FDG-PET) the neural substrates of impaired episodic specificity of autobiographical memories in 35 aMCI patients compared with 24 healthy elderly controls. Significant correlations between regional cerebral activity and the proportion of episodic details in autobiographical memories from two life periods were found in specific regions of an autobiographical brain network. In aMCI patients, more than in controls, specifically episodic memories from early adulthood were associated with metabolic activity in the cuneus and in parietal regions. We hypothesized that variable retrieval of episodic autobiographical memories in our aMCI patients would be related to their variable capacity to reactivate specific sensory-perceptual and contextual details of early adulthood events linked to reduced (occipito-parietal) visual imagery and less efficient (parietal) attentional processes. For recent memories (last year), a correlation emerged between the proportion of episodic details and activity in lateral temporal regions and the temporo-parietal junction. Accordingly, variable episodic memory for recent events may be related to the efficiency of controlled search through general events likely to provide cues for the retrieval of episodic details and to the ability to establish a self perspective favouring recollection. [less ▲]

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See detailItem familiarity and controlled associative retrieval in Alzheimer's disease: An fMRI study
Genon, Sarah ULg; Collette, Fabienne ULg; Feyers, Dorothée ULg et al

in Cortex : A Journal Devoted to the Study of the Nervous System & Behavior (2013), 49

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See detailBenevolent sexism alters executive brain responses
Dardenne, Benoît ULg; Dumont, Murielle; Sarlet, Marie et al

in Neuroreport (2013), 24(10), 572-577

Benevolence is widespread in our societies. It is defined as considering a subordinate group nicely but condescendingly, that is, with charity. Deleterious consequences for the target have been reported ... [more ▼]

Benevolence is widespread in our societies. It is defined as considering a subordinate group nicely but condescendingly, that is, with charity. Deleterious consequences for the target have been reported in the literature. In this experiment, we used functional MRI (fMRI) to identify whether being the target of (sexist) benevolence induces changes in brain activity associated with a working memory task. Participants were confronted by benevolent, hostile, or neutral comments before and while performing a reading span test in an fMRI environment. fMRI data showed that brain regions associated previously with intrusive thought suppression (bilateral, dorsolateral,prefrontal, and anterior cingulate cortex) reacted specifically to benevolent sexism compared with hostile sexism and neutral conditions during the performance of the task. These findings indicate that, despite being subjectively positive, benevolence modifies task-related brain networks by recruiting supplementary areas likely to impede optimal cognitive performance. [less ▲]

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See detailFonctionnement mnésique et maladie d’Alzheimer
Salmon, Eric ULg; Bastin, Christine ULg

in Lettre des Académies (La) (2013), 29

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