References of "Garraux, Gaëtan"
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See detailFinger Tapping feature extraction in Parkinson's disease using low-cost accelerometers
Stamatakis, Julien; Cremers, Julien ULg; Macq, Benoït et al

in Proceedings 10th IEEE International Conference on Information Technology and Applications in Biomedicine (ITAB 2010) (2010)

The clinical hallmarks of Parkinson's disease (PD) are movement poverty and slowness (i.e. bradykinesia), muscle rigidity and limb tremor. The physicians usually quantify these motor disturbances by ... [more ▼]

The clinical hallmarks of Parkinson's disease (PD) are movement poverty and slowness (i.e. bradykinesia), muscle rigidity and limb tremor. The physicians usually quantify these motor disturbances by assigning a severity score according to validated but time-consuming clinical scales such as the Unified Parkinson's Disease Rating Scale (UPDRS) - part III. These clinical ratings are however prone to subjectivity and inter-rater variability. The PD medical community is therefore looking for a faster and more objective rating method. As a first step towards this goal, a tri-axial accelerometer-based system is proposed as patients are engaged in a repetitive finger tapping task, which is classically used to assess bradykinesia in the UPDRS-III. After developing the hardware, an algorithm has been developed, that automatically epoched the signal on a trial-by-trial basis and quantified, among others, movement speed, amplitude, hesitations or halts as validated by visual inspection of video recordings during the task. The results obtained in a PD patient and an healthy volunteer are presented. Preliminary results show that PD patients and healthy volunteers have different features profiles, so that a classifier could be set up to predict objective UPDRS-III scores. [less ▲]

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See detailAutomatic brain image reading for the differential diagnosis between atypical parkinsonian syndromes & Parkinson's disease
Garraux, Gaëtan ULg; Phillips, Christophe ULg; Lemaire, Christian ULg et al

in Movement Disorders : Official Journal of the Movement Disorder Society (2010), 25(7), 379-379

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See detailAutomatic stimulus-induced medial premotor cortex activation without perception or action
D'Ostilio, Kevin ULg; Garraux, Gaëtan ULg

Poster (2010)

Evidence from functional imaging studies suggests that well-established stimulus-action associations may induce an automatic activation of the motor preparation system even when there is no intention to ... [more ▼]

Evidence from functional imaging studies suggests that well-established stimulus-action associations may induce an automatic activation of the motor preparation system even when there is no intention to make the associated movement (Grezes & Decety, 2002). Here we investigated whether this automatic motor activation can also be elicited by visual stimuli that are not consciously perceived. However, previous subliminal masked experiments used supraliminal response-target in such a way that unconscious mechanisms were inferred from the accumulation of the effect of the subliminal masked stimulus and the motor response. Here, to investigate neural correlates of unconscious process induced by subliminal stimuli, we used event-related BOLD fMRI at 3T to record brain activity in 24 healthy volunteers (mean age: 21 ± 2 years) as they performed a subliminal priming task (see Eimer & Schlaghecken, 1998). In this visuomotor task, participants were asked to make speeded button presses with the left or right hand following double leftward (<< <<) or rightward (>> >>) pointing arrows, which were preceded by a masked subliminal prime of 17 ms (compatible/incompatible arrows or neutral stimulus). Reaction time analysis revealed the classical positive compatibility effect (PCE), mainly shorter reaction times for compatible (mean RT: 369±38 ms) than for incompatible (mean RT: 383± 30 ms) in comparison to neutral trials (mean RT: 375± 38 ms). In a prime identification task, subjects’ performance was at chance level for primes presented for 17 ms, suggesting that the prime was not consciously perceived in the main experiment. Theses behavioral results suggest an automatic and unconscious motor activation induced by the prime. The responded stimuli were randomly intermixed with non-responded stimuli (0 0) with the assumption that the subliminal arrow prime also elicited an automatic motor activation in these passive trials as in responded trials. Imaging analysis of these non-responded trials showed first that activation was mainly restricted to posterior brain areas when using a subliminal stimulus that has not been previously associated with a motor response. Second, when the subliminal stimulus has been strongly associated with a motor response, this activation extended to rostral brain regions classically involved in motor preparation as the SMA, the premotor cortex and the striatum (cluster level p< 0.05 corrected). This finding corroborates the involvement of a fronto-striatal network, especially of the SMA in automatic and unconscious motor activation. [less ▲]

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See detail18F-flutemetamol amyloid imaging in Alzheimer disease and mild cognitive impairment: a phase 2 trial.
Vandenberghe, R.; Van Laere, K.; Ivanoiu, A. et al

in Annals of Neurology (2010), 68(3), 319-329

Objective: The most widely studied positron emission tomography ligand for in vivo -amyloid imaging is 11CPittsburgh compound B (11C-PIB). Its availability, however, is limited by the need for an on-site ... [more ▼]

Objective: The most widely studied positron emission tomography ligand for in vivo -amyloid imaging is 11CPittsburgh compound B (11C-PIB). Its availability, however, is limited by the need for an on-site cyclotron. Validation of the 18F-labeled PIB derivative 18F-flutemetamol could significantly enhance access to this novel technology. Methods: Twenty-seven patients with early-stage clinically probable Alzheimer disease (AD), 20 with amnestic mild cognitive impairment (MCI), and 15 cognitively intact healthy volunteers (HVs) above and 10 HVs below 55 years of age participated. The primary endpoint was the efficacy of blinded visual assessments of 18F-flutemetamol scans in assigning subjects to a raised versus normal uptake category, with clinical diagnosis as the standard of truth (SOT). As secondary objectives, we determined the correlation between the regional standardized uptake value ratios (SUVRs) for 18F-flutemetamol and its parent molecule 11C-PIB in 20 of the AD subjects and 20 of the MCI patients. We also determined test-retest variability of 18F-flutemetamol SUVRs in 5 of the AD subjects. Results: Blinded visual assessments of 18F-flutemetamol scans assigned 25 of 27 scans from AD subjects and 1 of 15 scans from the elderly HVs to the raised category, corresponding to a sensitivity of 93.1% and a specificity of 93.3% against the SOT. Correlation coefficients between cortical 18F-flutemetamol SUVRs and 11C-PIB SUVRs ranged from 0.89 to 0.92. Test-retest variabilities of regional SUVRs were 1 to 4%. Interpretation: 18F-Flutemetamol performs similarly to the 11C-PIB parent molecule within the same subjects and provides high test-retest replicability and potentially much wider accessibility for clinical and research use. [less ▲]

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See detailEvidence for distinct roles for basal ganglia and SMA in automatic and unconscious inhibition of voluntary actions
D'Ostilio, Kevin ULg; Garraux, Gaëtan ULg

Poster (2009, June)

Introduction: Although previous research highlighted the importance of automatic and unconscious inhibition in motor control, the neural correlates of such processes remain unclear. Basal ganglia ... [more ▼]

Introduction: Although previous research highlighted the importance of automatic and unconscious inhibition in motor control, the neural correlates of such processes remain unclear. Basal ganglia dysfunctions have long been associated with impairment in automatic motor control. In addition, Sumner & al. (2007) suggested a key role of the medial frontal cortex by administrating a masked priming task (e.g., Eimer & Schlaghecken 2003) to a patient with a small lesion restricted to the supplementary motor area (SMA)., Here, we used fMRI in normal subjects to better delineate the respective roles of SMA and basal ganglia in automatic and unconscious motor inhibition. Methods: We used event-related BOLD fMRI at 3T to record brain activity in 26 healthy volunteers (22 ± 2 years) as they performed the subliminal masked priming task. In this visuomotor task, participants are asked to make speeded button presses with the left or right hand following leftward or rightward pointing arrows, which are preceded by masked prime arrows. Here, two experimental variables were manipulated: the interval between the mask and the target (SOA: 0,100,150,200 or 250 ms) and the prime/target direction (compatible or incompatible). Imaging data processing and analysis were performed using SPM8b. Results: using Repeated Measures ANOVA of behavioral data (global interaction SOA*compatibility, p<0.0000001), we replicated the masked priming effects showing faster reaction times (i.e., motor response facilitation) in compatible than incompatible trials at 0-SOA (positive compatibility effect: diff = 21 ms, linear contrast : p<0.0000001) and the reverse (negative compatibility effect) at 100 (diff = -12 ms, p= 0.01) and 150-SOA (diff= -12 ms, p= 0.008) suggesting motor response inhibition. At 200 & 250 SOA, we no longer found significant compatibility effects (p>0.05) By applying a similar statistical model to imaging data, we observed a stronger activity in the in several regions, the SMA (p<0.001, uncorrected), caudate (p=0.002, uncorrected) and thalamus (p<0.001, uncorrected) showing stronger activity in compatible than incompatible trials at 100 and 150-SOA, as compared with 0-SOA. Moreover, the differential activity in the SMA was correlated with the negative compatibility effect (p= 0.01). When testing for a main effect of SOAs we didn’t find a differential activation of the SMA, but a stronger deactivation of the caudate (p=0.009, uncorrected) and the thalamus (p=0.007, uncorrected) at 100-150 SOA (inhibition conditions) compared to 0-SOA (facilitation condition). In a prime identification task administered after the fMRI experiment, subjects’ performance was at chance levels for primes displayed for 17 ms as in the main study, suggesting that the prime was not consciously perceived. Conclusions: These new findings suggest that automatic and unconscious inhibition of an activated motor response is mediated by the basal ganglia whereas medial frontal regions seem to be more implicated in the control of response conflict related to inhibition. [less ▲]

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See detailLa vignette thérapeutique de l'étudiant. La maladie de Parkinson debutante
DELVAUX, Valérie ULg; MOONEN, Gustave ULg; Garraux, Gaëtan ULg

in Revue Médicale de Liège (2009), 64(4), 228-32

We present a discussion on the treatment options in the case of a patient seen at the outpatient abnormal movement clinic for a resting tremor of both hands. Signs and symptoms of the parkinsonian ... [more ▼]

We present a discussion on the treatment options in the case of a patient seen at the outpatient abnormal movement clinic for a resting tremor of both hands. Signs and symptoms of the parkinsonian syndrome are summarized as well as the current treatment options of early Parkinson's disease. [less ▲]

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See detailDifferential diagnosis of dementia using functional neuroimaging
Salmon, Eric ULg; Collette, Fabienne ULg; Garraux, Gaëtan ULg

in Jagust, William; D'Esposito, Mark (Eds.) Imaging the aging brain (2009)

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See detailA clinico-pathological report of SCA17 associated with a heterozygote small trinucleotide expansion
Garraux, Gaëtan ULg; Moonen, Gustave ULg; Deprez, Manuel ULg

in Movement Disorders : Official Journal of the Movement Disorder Society (2009), 24(Suppl. 1), 12-12

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See detailUnified Freezing of Gait Rating Scale (UFOGS)
Cremers, Julien ULg; Garraux, Gaëtan ULg

in Movement Disorders : Official Journal of the Movement Disorder Society (2009), 24(Suppl. 1), 432-433

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See detailEvidence for increased upper brain stem activity following STN-DBS in Parkinson's disease: An (18)FDG-PET study
Desoullieres, Aurélie; KASCHTEN, Bruno ULg; CREMERS, Julien ULg et al

in Movement Disorders : Official Journal of the Movement Disorder Society (2009), 24(Suppl. 1), 186-187

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See detailDe novo interstitial duplication 4q associated with sporadic young-onset dopa-responsive parkinsonism
Garraux, Gaëtan ULg; VANBELLINGHEN, Jean-François ULg; JAMAR, Mauricette ULg et al

in Movement Disorders : Official Journal of the Movement Disorder Society (2009), 24(Suppl. 1), 138-139

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See detailFunctional imaging of cognition in Alzheimer's disease using positron emission tomography
Salmon, Eric ULg; Lekeu, Françoise ULg; Garraux, Gaëtan ULg et al

in Neuropsychologia (2008), 46(6), 1613-1623

Positron emission tomography in Alzheimer's disease (AD) demonstrates a metabolic decrease, predominantly in associative posterior cortices (comprising the posterior cingulate cortex), and also involving ... [more ▼]

Positron emission tomography in Alzheimer's disease (AD) demonstrates a metabolic decrease, predominantly in associative posterior cortices (comprising the posterior cingulate cortex), and also involving medial temporal structures and frontal regions at a lesser degree. The level of activity in this wide network is roughly correlated with dementia severity, but several confounds (such as age, education or subcortical ischemic lesions) may influence the brain-behaviour relationship. Univariate analyses allow one to segregate brain regions that are particularly closely related to specific neuropsychological performances. For example, a relationship was established between the activity in lateral associative cortices and semantic performance in AD. The role of semantic capacities (subserved by temporal or parietal regions) in episodic memory tasks was also emphasized. The residual activity in medial temporal structures was related to episodic memory abilities, as measured by free recall performance, cued recall ability and recognition accuracy. More generally, AD patients' performance on episodic memory tasks was correlated with the metabolism in several structures of Papez's circuit (including the medial temporal and posterior cingulate regions). Multivariate analyses should provide complementary information on impaired metabolic covariance in functional networks of brain regions and the consequences for AD patients' cognitive performance. More longitudinal studies are being conducted that should tell us more about the prognostic value of initial metabolic impairment and the neural correlates of progressive deterioration of cognitive performance in AD. [less ▲]

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See detailMetabolic correlates of clinical heterogeneity in questionable Alzheimer’s disease
Salmon, Eric ULg; Lekeu, Françoise ULg; Garraux, Gaëtan ULg et al

in Neurobiology of Aging (2008), 29

Thirty-four subjects with questionable Alzheimer's disease (QAD) were included in a 3-year prospective study and underwent neuropsychological testing and measurement of brain metabolism using FDG-PET at ... [more ▼]

Thirty-four subjects with questionable Alzheimer's disease (QAD) were included in a 3-year prospective study and underwent neuropsychological testing and measurement of brain metabolism using FDG-PET at entry. Seventeen patients (50%) did not convert to AD during the follow-up period. Compared to elderly controls of similar age, the cerebral activity of non-converters was reduced in the dorsolateral prefrontal cortex. Moreover, the variability of metabolism in the posterior cingulate cortex was related to their visuospatial memory performance, while disparity in parietal activity was related to their verbal memory performance. These results demonstrate the cerebral metabolic heterogeneity of patients with QAD. Initial functional images of converters showed that activity was already impaired in the posterior cingulate, lateral temporal cortex, anterior cingulate and orbitofrontal cortex. This metabolic pattern is consistent with a pre-dementia stage of AD, and highlights the fact that significant frontal metabolic involvement may be associated with impaired activity in posterior associative cortices in very early AD. [less ▲]

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See detailPreserver le fonctionnement du cerveau...par la pratique d'une activite physique?
Garraux, Gaëtan ULg

in Revue Médicale de Liège (2008), 63(5-6), 293-8

Over the last few years, there has been an increasing interest in the relationship between brain function and physical exercise. Preliminary evidence from observational and interventional studies in ... [more ▼]

Over the last few years, there has been an increasing interest in the relationship between brain function and physical exercise. Preliminary evidence from observational and interventional studies in humans suggests a positive and robust effect of chronic aerobic exercise on several brain functions across the entire lifespan. Physical activity and exercise might also serve to reduce the risk of age-associated neurological disorders such as Alzheimer's and Parkinson's diseases. The mechanisms underlying these beneficial effects remain poorly understood. More scientific work is needed before disseminating more specific recommendations to the general population. [less ▲]

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See detailLevodopa increases memory encoding and dopamine release in the striatum in the elderly.
Floel, Agnes; Garraux, Gaëtan ULg; Xu, Ben et al

in Neurobiology of Aging (2008), 29(2), 267-79

Normal aging is associated with a decrease in dopaminergic function and a reduced ability to form new motor memories with training. This study examined the link between both phenomena. We hypothesized ... [more ▼]

Normal aging is associated with a decrease in dopaminergic function and a reduced ability to form new motor memories with training. This study examined the link between both phenomena. We hypothesized that levodopa would (a) ameliorate aging-dependent deficits in motor memory formation, and (b) increase dopamine availability at the dopamine type 2-like (D2) receptor during training in task-relevant brain structures. The effects of training plus levodopa (100mg, plus 25mg carbidopa) on motor memory formation and striatal dopamine availability were measured with [(11)C]raclopride (RAC) positron emission tomography (PET). We found that levodopa did not alter RAC-binding potential at rest but it enhanced training effects on motor memory formation as well as dopamine release in the dorsal caudate nucleus. Motor memory formation during training correlated with the increase of dopamine release in the caudate nucleus. These results demonstrate that levodopa may ameliorate dopamine deficiencies in the elderly by replenishing dopaminergic presynaptic stores, actively engaged in phasic dopamine release during motor training. [less ▲]

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See detailGesture Subtype-Dependent Left Lateralization of Praxis Planning: An Event-Related fMRI Study.
Bohlhalter, Stephan; Hattori, Nori; Wheaton, Lewis et al

in Cerebral Cortex (2008)

Ideomotor apraxia is a disorder mainly of praxis planning, and the deficit is typically more evident in pantomiming transitive (tool related) than intransitive (communicative) gestures. The goal of the ... [more ▼]

Ideomotor apraxia is a disorder mainly of praxis planning, and the deficit is typically more evident in pantomiming transitive (tool related) than intransitive (communicative) gestures. The goal of the present study was to assess differential hemispheric lateralization of praxis production using event-related functional magnetic resonance imaging. Voxel-based analysis demonstrated significant activations in posterior parietal cortex (PPC) and premotor cortex (PMC) association areas, which were predominantly left hemispheric, regardless of whether planning occurred for right or left hand transitive or intransitive pantomimes. Furthermore, region of interest-based calculation of mean laterality index (LI) revealed a significantly stronger left lateralization in PPC/PMC clusters for planning intransitive (LI = -0.49 + 0.10, mean + standard deviation [SD]) than transitive gestures (-0.37 + 0.08, P = 0.02, paired t-tests) irrespective of the hand involved. This differential left lateralization for planning remained significant in PMC (LI = -0.47 + 0.14 and -0.36 + 0.13, mean + SD, P = 0.04), but not in PPC (-0.56 + 0.11 and -0.45 + 0.12, P = 0.11), when both regions were analyzed separately. In conclusion, the findings point to a left-hemispheric specialization for praxis planning, being more pronounced for intransitive gestures in PMC, possibly due to their communicative nature. [less ▲]

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See detailTherapeutic armamentarium in neurology: the birth of a new era
Belachew, Shibeshih ULg; Magis, Delphine ULg; Lievens, Isabelle ULg et al

in Revue Médicale de Liège (2007), 62(5-6), 432-448

The field of neurology was long infamous for a lack of therapeutic options. How many of you have once thought: "Neurologists don't cure the disease, they admire it". But those days have passed into ... [more ▼]

The field of neurology was long infamous for a lack of therapeutic options. How many of you have once thought: "Neurologists don't cure the disease, they admire it". But those days have passed into history, and the field is now vibrant with new treatments and hope even for patients with the worst neurodegenerative diseases. We summarized in the present review the latest major advances in therapeutic principles and practice for some of the most frequent chronic neurological disorders such as headaches, epilepsy, multiple sclerosis, dementias, Parkinson's disease, sleep/wake disturbances and peripheral neuropathies. We cannot cure or prevent, but we can now halt or control symptoms and disease progression to provide physical and psychological relief, and a better quality of life for patients who suffer from these otherwise devastating neurological conditions. [less ▲]

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See detailModulation of cerebral functional interactions by cortical dopamine in health and Parkinson's disease
Garraux, Gaëtan ULg; Talagala, S.; Carson, R. et al

in Movement Disorders : Official Journal of the Movement Disorder Society (2007), 22(Suppl. 16), 478

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