References of "Garraux, Gaëtan"
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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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See detailA Synthesis of Functional Neuroimaging in the Frontal Variant of Frontotemporal Dementia
Salmon, Eric ULg; Garraux, Gaëtan ULg; Collette, Fabienne ULg

in Current Medical Imaging Reviews (2007), 3(2), 117-121

The frontal variant of frontotemporal dementia (fvFTD) is clinically characterized by a disruption of the social behaviour. Frontotemporal decrease of activity on functional imaging is an independent ... [more ▼]

The frontal variant of frontotemporal dementia (fvFTD) is clinically characterized by a disruption of the social behaviour. Frontotemporal decrease of activity on functional imaging is an independent marker of the disease. Principal component analysis of cerebral functional images reveals one ensemble comprising both frontal lobes, and two lateralized clusters comprising temporal and subcallosal frontal regions. Executive dysfunction and verbal difficulties are shown to interact in fvFTD, and they are related to large scale frontal and temporal neural networks in the disease. The neural substrate of the memory impairments in patients with fvFTD is also heterogeneous, since correlations were observed with frontal activity, but also with medial temporal atrophy. Behavioural changes are the hallmarks of fvFTD. Apathy is consistently related to frontal involvement, while disinhibition occurs in patients with predominant posterior orbitofrontal and temporal involvement. The consequences of lateralized brain lesions remain a matter of debate, since impulsive and compulsive behaviour was evenly related to right or left temporal involvement in fvFTD. Those patients know social rules, but they are impaired in assessing the importance of social transgressions and in recognizing emotions. Processing transgressions of social norms results in a complex activation of medial prefrontal, orbitofrontal and temporal regions in control populations. The variable decrease in these regional activities observed in different fvFTD patients would explain their complex, individual social disturbance. [less ▲]

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See detailNeuroimaging of neuronal circuits involved in tic generation in patients with Tourette syndrome.
Lerner, Alicja; Bagic, Anto; Boudreau, Elis et al

in Neurology (2007), 68(23), 1979-87

OBJECTIVE: To identify brain regions generating tics in patients with Tourette syndrome using sleep as a baseline. METHODS: We used [15O]H2O PET to study nine patients with Tourette syndrome and nine ... [more ▼]

OBJECTIVE: To identify brain regions generating tics in patients with Tourette syndrome using sleep as a baseline. METHODS: We used [15O]H2O PET to study nine patients with Tourette syndrome and nine matched control subjects. For patients, conditions included tic release states and sleep stage 2; and for control subjects, rest states and sleep stage 2. RESULTS: Our study showed robust activation of cerebellum, insula, thalamus, and putamen during tic release. CONCLUSION: The network of structures involved in tics includes the activated regions and motor cortex. The prominent involvement of cerebellum and insula suggest their involvement in tic initiation and execution. [less ▲]

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See detailTask-related interaction between basal ganglia and cortical dopamine release.
Garraux, Gaëtan ULg; Peigneux, Philippe ULg; Carson, Richard E et al

in Journal of Neuroscience (2007), 27(52), 14434-41

Dopamine (DA) is a powerful neuromodulator for a wide variety of behaviors. Considerable evidence accumulated from rodent and monkey experiments over the last two decades suggests that DA activity in the ... [more ▼]

Dopamine (DA) is a powerful neuromodulator for a wide variety of behaviors. Considerable evidence accumulated from rodent and monkey experiments over the last two decades suggests that DA activity in the frontal cortex is reciprocally linked to that in functionally related basal ganglia (BG) structures. However, the functional importance of this in humans is still unknown. To address this issue, we measured endogenous DA release using positron emission tomography in 15 healthy subjects as they practiced the first training session of a finger sequence learning task. Significant results were observed not only in striatal areas but also in extrastriatal "motor" regions, bilaterally. Faster learning was specifically coupled to lower DA release in the sensorimotor part of the globus pallidus pars interna (GPi) contralateral to the moving hand, which was paralleled by a higher increase in DA levels in the pre-supplementary motor area (pre-SMA). This finding provides original evidence supporting a motor-learning-related interaction between DA release in left GPi and pre-SMA, a mechanism that may also apply to other anatomically and functionally interconnected BG and frontal cortical areas as a function of behavior. [less ▲]

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See detailNeural correlates of anosognosia for cognitive impairment in Alzheimer's disease
Salmon, Eric ULg; Perani, D.; Herholz, K. et al

in Human Brain Mapping (2006), 27(7), 588-597

We explored the neural substrate of anosognosia for cognitive impairment in Alzheimer's disease (AD). Two hundred nine patients with mild to moderate dementia and their caregivers assessed patients ... [more ▼]

We explored the neural substrate of anosognosia for cognitive impairment in Alzheimer's disease (AD). Two hundred nine patients with mild to moderate dementia and their caregivers assessed patients' cognitive impairment by answering a structured questionnaire. Subjects rated 13 cognitive domains as not impaired or associated with mild, moderate, severe, or very severe difficulties, and a sum score was calculated. Two measures of anosognosia were derived. A patient's self assessment, unconfounded by objective measurements of cognitive deficits such as dementia severity and episodic memory impairment, provided an estimate of impaired self-evaluative judgment about cognition in AD. Impaired self-evaluation was related to a decrease in brain metabolism measured with 18F-2-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) in orbital prefrontal cortex and in medial temporal structures. In a cognitive model of anosognosia, medial temporal dysfunction might impair a comparison mechanism between current information on cognition and personal knowledge. Hypoactivity in orbitofrontal cortex may not allow AD patients to update the qualitative judgment associated with their impaired cognitive abilities. Caregivers perceived greater cognitive impairments than patients did. The discrepancy score between caregiver's and patient's evaluations, an other measure of anosognosia, was negatively related to metabolic activity located in the temporoparietal junction, consistent with an impairment of self-referential processes and perspective taking in AD. [less ▲]

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See detailDecomposition of metabolic brain clusters in the frontal variant of frontotemporal dementia
Salmon, Eric ULg; Kerrouche, Nacer; Herholz, Karl et al

in NeuroImage (2006), 30(3), 871-878

Previous studies that measured brain activity in frontotemporal dementia (FTD) used univariate analyses, examining each region of interest separately. We explored in a multicenter European research ... [more ▼]

Previous studies that measured brain activity in frontotemporal dementia (FTD) used univariate analyses, examining each region of interest separately. We explored in a multicenter European research program the principal brain clusters characterized by a common variability in cerebral metabolism in FTD. Seventy patients with frontal variant (fv) FTD were selected according to international clinical recommendations; principal component analysis (PCA) was performed on FDG-PET metabolic images, looking for covariance clusters in this large population. A first metabolic cluster included most of the lateral and medial prefrontal cortex, bilaterally; PC1 scores correlated with performances on memory and executive neuropsychological tasks. Moreover, FDG-PET images in fv-FTD were further characterized by a metabolic covariance in two clusters comprising the subcallosal medial frontal region, the temporal pole, medial temporal structures and the striatum, separately in the left and in the right hemisphere. The study provides original data-driven arguments for metabolic involvement of separate brain clusters in the rostral limbic system, corresponding to pathological poles differentially affected in each FTD patient. [less ▲]

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See detailIncreased midbrain gray matter in Tourette's syndrome
Garraux, Gaëtan ULg; Goldfine, Andrew; Bohlhalter, Stephan et al

in Annals of Neurology (2006), 59(2), 381-385

Objective: To investigate cerebral structure in Tourette's syndrome (TS). Methods: Voxel-based morphometry study of high-resolution MRIs in 31 TS patients compared with 31 controls. Results: Increased ... [more ▼]

Objective: To investigate cerebral structure in Tourette's syndrome (TS). Methods: Voxel-based morphometry study of high-resolution MRIs in 31 TS patients compared with 31 controls. Results: Increased gray matter mainly in the left mesencephalon in 31 TS patients. Interpretation: This result constitutes strong and direct evidence supporting Devinsky's hypothesis (Devinsky O. Neuroanatomy of Gilles de la Tourette's syndrome. Possible midbrain involvement. Arch Neurol 1983;40:508514) according to which midbrain disturbances play an important pathogenic role in TS. [less ▲]

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See detailHippocampal response at training promotes insight after sleep
Darsaud, Annabelle; Balteau, Evelyne ULg; Desseilles, Martin ULg et al

in NeuroImage (2006), 31(Suppl. 1),

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See detailNeural correlates of tic generation in Tourette syndrome: an event-related functional MRI study.
Bohlhalter, Stephan; Goldfine, Andrew; Matteson, S. et al

in Brain : A Journal of Neurology (2006), 129(Pt 8), 2029-37

Little is known about the neural correlates of tics and associated urges. In the present study, we aimed to explore the neural basis of tics in patients with Tourette syndrome by using event-related ... [more ▼]

Little is known about the neural correlates of tics and associated urges. In the present study, we aimed to explore the neural basis of tics in patients with Tourette syndrome by using event-related functional MRI (fMRI). Ten patients (6 women, 4 men; age: mean +/- SD = 31 +/- 11.2) were studied while spontaneously exhibiting a variety of motor and vocal tics. On the basis of synchronized video/audio recordings, fMRI activities were analysed 2 s before and at tic onset irrespective of the clinical phenomenology. We identified a brain network of paralimbic areas such as anterior cingulate and insular cortex, supplementary motor area (SMA) and parietal operculum (PO) predominantly activated before tic onset (P < 0.05, corrected for multiple comparisons). In contrast, at the beginning of tic action, significant fMRI activities were found in sensorimotor areas including superior parietal lobule bilaterally and cerebellum. The results of this study indicate that paralimbic and sensory association areas are critically implicated in tic generation, similar to movements triggered internally by unpleasant sensations, as has been shown for pain or itching. [less ▲]

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See detailNeural correlates of counting of sequential sensory and motor events in the human brain.
Kansaku, Kenji; Johnson, Ari; Grillon, Marie-Laure et al

in NeuroImage (2006), 31(2), 649-60

Little is known about the ability to enumerate small numbers of successive stimuli and movements. It is possible that there exist neural substrates that are consistently recruited both to count sensory ... [more ▼]

Little is known about the ability to enumerate small numbers of successive stimuli and movements. It is possible that there exist neural substrates that are consistently recruited both to count sensory stimuli from different modalities and for counting movements executed by different effectors. Here, we identify a network of areas that was involved in enumerating small numbers of auditory, visual, and somatosensory stimuli, and in enumerating sequential movements of hands and feet, in the bilateral premotor cortex, presupplementary motor area, posterior temporal cortex, and thalamus. The most significant consistent activation across sensory and motor counting conditions was found in the lateral premotor cortex. Lateral premotor activation was not dependent on movement preparation, stimulus presentation timing, or number word verbalization. Movement counting, but not sensory counting, activated the anterior parietal cortex. This anterior parietal area may correspond to an area recruited for movement counting identified by recent single-neuron studies in monkeys. These results suggest that overlapping but not identical networks of areas are involved in counting sequences of sensory stimuli and sequences of movements in the human brain. [less ▲]

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See detailClinical contribution of PET neurotransmission imaging in neurological disorders
Garraux, Gaëtan ULg; Salmon, Eric ULg

in Acta Neurologica Belgica (2005), 105(3), 119-136

Imaging neurotransmission in vivo using positron emission tomography (PET) is a rapidly expanding clinical science. The present review summarizes the actual contribution of PET imaging to clinical ... [more ▼]

Imaging neurotransmission in vivo using positron emission tomography (PET) is a rapidly expanding clinical science. The present review summarizes the actual contribution of PET imaging to clinical problems in movement and seizure disorders and dementia. [less ▲]

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