Accidents vasculaires cérébraux : neuropsychologie, imagerie multimodale, remédiation cognitive et traitement pharmacologique

Si les séquelles fonctionnelles des Accidents Vasculaires Cérébraux (AVC) sont fréquentes et responsables de déficits moteur, sensitif et langagier, les séquelles cognitives invisibles, contribuent au handicap. Tout au long de ce travail, nous dessinerons le profil neuropsychologique de patients victimes d'un accident ischémique transitoire, d'un AVC ischémique et hémorragique. Nous verrons ensuite dans quelles mesures les mécanismes de plasticité cérébrale sont mis en jeu dans l'ischémie cérébrale et comment il est possible de moduler les réseaux fonctionnels de la cognition via une prise en charge en remédiation cognitive. Il s'agira enfin d'aborder la physiopathologie des hémorragies intracérébrales à l'aide de marqueurs cliniques, anatomiques et moléculaires dans le but de mieux caractériser l'étiologie de la maladie et ainsi aider au diagnostic clinique.If the functional outcomes of stroke are common and closely related to motor, sensory and language deficits, cognitive disorders, invisible, contribute significantly to the disability and are still poorly understood in the general population. Throughout this work, we will draw the neuropsychological profile of patients victim of a transient ischemic attack, ischemic and hemorrhagic stroke. We will then see in which extend the mechanisms of brain plasticity are involved in cerebral ischemia, and how it is possible to modulate the functional networks of cognition thru cognitive remediation. We will finally discuss the pathophysiology of intracerebral hemorrhage using clinical, anatomical and molecular markers in order to better characterize the etiology of the disease and thus help clinical diagnosis

ERP and behavioral evidence for interaction/cascade between central (linguistic) and peripheral (motor) processes during word handwriting

International audienceModels of handwritten language production make a distinction between central (access to semantic, orthographic and phonological information) and peripheral (allographic and gesture planning) processes (see van Galen, 1991; Rapp, 2002). Though, this is still a matter of debate whether these central and peripheral modules are processed in a cascaded or in a serial way (Delattre, Barry & Bonin, 2006; Damian & Stadthagen-Gonzalez, 2009). In the same view, another question still debated is ”do central and peripheral processes ‘interact’ in handwritten word production compared to oral naming”

Clinical heterogeneity of neuro-inflammatory PET profiles in early Alzheimer’s disease

The relationship between neuroinflammation and cognition remains uncertain in early Alzheimer’s disease (AD). We performed a cross-sectional study to assess how neuroinflammation is related to cognition using TSPO PET imaging and a multi-domain neuropsychological assessment. A standard uptake value ratio (SUVR) analysis was performed to measure [18F]-DPA-714 binding using the cerebellar cortex or the whole brain as a (pseudo)reference region. Among 29 patients with early AD, the pattern of neuroinflammation was heterogeneous and exhibited no correlation with cognition at voxel-wise, regional or whole-brain level. The distribution of the SUVR values was independent of sex, APOE phenotype, early and late onset of symptoms and the presence of cerebral amyloid angiopathy. However, we were able to demonstrate a complex dissociation as some patients with similar PET pattern had opposed neuropsychological profiles while other patients with opposite PET profiles had similar neuropsychological presentation. Further studies are needed to explore how this heterogeneity impacts disease progression

In-vivo diagnosis of cerebral amyloid angiopathy: an updated review

International audiencePurpose of review: Sporadic cerebral amyloid angiopathy (CAA) is a highly prevalent small vessel disease in ageing population with potential severe complications including lobar intracerebral hemorrhage (ICH), cognitive impairment, and dementia. Although diagnosis of CAA was made only with postmortem neuropathological examination a few decades ago, diagnosing CAA without pathological proof is now allowed in living patients. This review focuses on recently identified biomarkers of CAA and current diagnostic criteria.Recent findings: Over the past few years, clinicians and researchers have shown increased interest for CAA, and important advances have been made. Thanks to recent insights into mechanisms involved in CAA and advances in structural and functional neuroimaging, PET amyloid tracers, cerebrospinal fluid and plasma biomarkers analysis, a growing number of biomarkers of CAA have been identified. Imaging-based diagnostic criteria including emerging biomarkers have been recently developed or updated, enabling accurate and earlier diagnosis of CAA in living patients.Summary: Recent advances in neuroimaging allow diagnosing CAA in the absence of pathological examination. Current imaging-based criteria have high diagnostic performance in patients presenting with ICH, but is more limited in other clinical context such as cognitively impaired patients or asymptomatic individuals. Further research is still needed to improve diagnostic accuracy

The “handwriting brain”: a motor/linguistic network with specialized “writing-specific” areas?

International audienceSince the first lesion studies from the late nineteenth century until the advent of functional neuroimaging, the uncovering of the cerebral substrates of written production raised the question of the existence of a “writing center” in the brain. A number of neuroimaging studies with healthy subjects have highlighted a broad network of brain areas, some being involved in linguistic processing or in motor control of handwriting, and some playing a “writing-specific” role. Those studies also reported inconsistent results, probably resulting from the diversity of methodologies used. In order to clear up discrepancies, we conducted a meta-analysis of 18 neuroimaging studies involving written language production (using the ALE method). We were thereby able to identify a network of 12 cortical and subcortical areas, mainly on the left hemisphere. Three areas were considered as primarily writing-specific (left SFS/MFG area, left IPS/SPL area, right cerebellum) while the others were more related to non-specific motor (M1/SM1, SMA, thalamus and putamen) or linguistic processes (vPM, PITC) (Planton, Jucla, Roux & Démonet, 2013). We then aim at testing the functional specificity to handwriting of the identified areas with a specific focus on the lateralization of brain response. To do so, we conducted an fMRI experiment in which written naming was compared to drawing and to oral spelling. We extracted BOLD activity within 4 volumes of interests (and their right - or left- counterpart), based on the coordinates from the meta-analysis work (left SFS, left IPS, left vPM, right cerebellum), and compared it across tasks. Results showed that the hypothesis of specificity is questioned when focusing only on the intensity of activation, and that taking into account the inter-hemispheric balance can be an effective way to understand the functional contribution of each of these areas within the whole writing process (Planton, Péran, Longcamp, Démonet & Jucla, in prep)

The “handwriting brain”: a motor/linguistic network with specialized “writing-specific” areas?

International audienceSince the first lesion studies from the late nineteenth century until the advent of functional neuroimaging, the uncovering of the cerebral substrates of written production raised the question of the existence of a “writing center” in the brain. A number of neuroimaging studies with healthy subjects have highlighted a broad network of brain areas, some being involved in linguistic processing or in motor control of handwriting, and some playing a “writing-specific” role. Those studies also reported inconsistent results, probably resulting from the diversity of methodologies used. In order to clear up discrepancies, we conducted a meta-analysis of 18 neuroimaging studies involving written language production (using the ALE method). We were thereby able to identify a network of 12 cortical and subcortical areas, mainly on the left hemisphere. Three areas were considered as primarily writing-specific (left SFS/MFG area, left IPS/SPL area, right cerebellum) while the others were more related to non-specific motor (M1/SM1, SMA, thalamus and putamen) or linguistic processes (vPM, PITC) (Planton, Jucla, Roux & Démonet, 2013). We then aim at testing the functional specificity to handwriting of the identified areas with a specific focus on the lateralization of brain response. To do so, we conducted an fMRI experiment in which written naming was compared to drawing and to oral spelling. We extracted BOLD activity within 4 volumes of interests (and their right - or left- counterpart), based on the coordinates from the meta-analysis work (left SFS, left IPS, left vPM, right cerebellum), and compared it across tasks. Results showed that the hypothesis of specificity is questioned when focusing only on the intensity of activation, and that taking into account the inter-hemispheric balance can be an effective way to understand the functional contribution of each of these areas within the whole writing process (Planton, Péran, Longcamp, Démonet & Jucla, in prep)

Effects of orthographic consistency and word length on the dynamics of written production in adults: psycholinguistic and rTMS experiments

Recent studies on written word production aim at studying how information is transmitted between central (linguistic) and peripheral (motor) processes. Neurocognitive models propose that the interface between both types of processes would rely on a frontal writing center (i.e. the GMFA or Exner's area). However there is still debate (1) whether those levels are processed in a serial or a cascaded/parallel way and (2) about the nature of the contribution of the GMFA. In Experiment 1, we evaluated the interaction between length and orthographic consistency effects in a writing-to-dictation task. We observed consistency effects on latencies and writing speed depending on the position in the word of the inconsistent segment. In Experiment 2, 16 participants underwent a writing-to-dictation task, manipulating length and regularity effect, after inhibitory rTMS. We observed an increase of latencies restricted to long and irregular words. Those results are consistent with a cascaded view of writing and suggest a more complex role of GMFA than initially expected

ERP and behavioral evidence for interaction/cascade between central (linguistic) and peripheral (motor) processes during word handwriting

International audienceModels of handwritten language production make a distinction between central (access to semantic, orthographic and phonological information) and peripheral (allographic and gesture planning) processes (see van Galen, 1991; Rapp, 2002). Though, this is still a matter of debate whether these central and peripheral modules are processed in a cascaded or in a serial way (Delattre, Barry & Bonin, 2006; Damian & Stadthagen-Gonzalez, 2009). In the same view, another question still debated is ”do central and peripheral processes ‘interact’ in handwritten word production compared to oral naming”

Update on the Efficacy of Cognitive Rehabilitation After Moderate to Severe Traumatic Brain Injury: A Scoping Review

International audienceObjectives: To identify, categorize, and analyze the methodological issues of cognitive rehabilitation of patients with moderate to severe traumatic brain injury and its efficacy.Data sources: Pubmed and PsycINFO were searched for studies published between 2015 and 2021 using keywords for cognitive intervention and traumatic brain injury.Study selection: Two independent reviewers selected articles concerning cognitive rehabilitation for adults with traumatic brain injury. Of 458 studies, 97 full-text articles were assessed and 46 met the inclusion criteria.Data extraction: Data were analyzed by 1 reviewer according to criteria concerning the methodological quality of studies.Data synthesis: Results showed a large scope of 7 cognitive domains targeted by interventions, delivered mostly in individual sessions (83%) with an integrative cognitive approach (48%). Neuroimaging tools as a measure of outcome remained scarce, featuring in only 20% of studies. Forty-three studies reported significant effects of cognitive rehabilitation, among which 7 fulfilled a high methodological level of evidence.Conclusions: Advances and shortcomings in cognitive rehabilitation have both been highlighted and led us to develop methodological key points for future studies. The choice of outcome measures, the selection of control interventions, and the use of combined rehabilitation should be investigated in further studies