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Motor hand deficits impact autonomy in everyday life, and neuroplasticity processes of motor recovery can be explored using functional MRI (fMRI). However, few studies have used fMRI to explore the mechanisms underlying hand recovery following stroke. Based on the dual visuomotor model positing that two segregated dorsomedial and dorsolateral cerebral networks control reach and grasp movements, we explored the relationship between motor task-related activity in the sensorimotor network and hand recovery following stroke. Behavioral recovery was explored with a handgrip force task assessing simple grasp, and a visuomotor reaching and precise grasping task, the Purdue Pegboard Test (PPT). We used a passive wrist flexion-extension task to measure fMRI activity in 36 sensorimotor brain areas. Behavioral and fMRI measurements were performed in 27 patients (53.2 ± 9.5 years) 1-month following stroke, and then 6-month and 24-month later. The effects of sensorimotor activity on hand recovery were analyzed using correlations and linear mixed models (LMMs). PPT and handgrip force correlated with fMRI activity measures in the sensorimotor and parietal areas. PPT recovery was modeled by fMRI measures in the ipsilesional primary motor cortex (MI-4p), superior parietal lobule (SPL-7M) and parietal operculum OP1, and lesion side. Handgrip force was modeled by ipsilesional MI-4a, OP1, and contralesional inferior parietal lobule (IPL-PFt). Moreover, the relationship between fMRI activity and hand recovery was time-dependent, occurring in the early recovery period in SPL-BA-7M, and later in MI. These results suggest that areas of both dorsolateral and dorsomedial networks participate to visuomotor reach and grasp tasks (PPT), while dorsolateral network areas may control recovery of simple grasp (handgrip force), suggesting that the type of movement modulates network recruitment. We also found functional dissociations between MI-4p related to PPT that required independent finger movements and MI-4a related to simple grasp without independent finger movements. These findings need to be replicated in further studies.

While motor recovery following mild stroke has been extensively studied with neuroimaging, mechanisms of recovery after moderate to severe strokes of the types that are often the focus for novel restorative therapies remain obscure. We used fMRI to: 1) characterize reorganization occurring after moderate to severe subacute stroke, 2) identify brain regions associated with motor recovery and 3) to test whether brain activity associated with passive movement measured in the subacute period could predict motor outcome six months later. Because many patients with large strokes involving sensorimotor regions cannot engage in voluntary movement, we used passive flexion-extension of the paretic wrist to compare 21 patients with subacute ischemic stroke to 24 healthy controls one month after stroke. Clinical motor outcome was assessed with Fugl-Meyer motor scores (motor-FMS) six months later. Multiple regression, with predictors including baseline (one-month) motor-FMS and sensorimotor network regional activity (ROI) measures, was used to determine optimal variable selection for motor outcome prediction. Sensorimotor network ROIs were derived from a meta-analysis of arm voluntary movement tasks. Bootstrapping with 1000 replications was used for internal model validation. During passive movement, both control and patient groups exhibited activity increases in multiple bilateral sensorimotor network regions, including the primary motor (MI), premotor and supplementary motor areas (SMA), cerebellar cortex, putamen, thalamus, insula, Brodmann area (BA) 44 and parietal operculum (OP1-OP4). Compared to controls, patients showed: 1) lower task-related activity in ipsilesional MI, SMA and contralesional cerebellum (lobules V-VI) and 2) higher activity in contralesional MI, superior temporal gyrus and OP1-OP4. Using multiple regression, we found that the combination of baseline motor-FMS, activity in ipsilesional MI (BA4a), putamen and ipsilesional OP1 predicted motor outcome measured 6 months later (adjusted-R2 = 0.85; bootstrap p, Highlights • Motor recovery after stroke can be robustly predicted using a passive task fMRI paradigm. • Sensorimotor network activity is decreased in moderate to severe stroke patients relative to healthy controls • Compensatory mechanisms in severe stroke involve both the dorsal (MI BA4a), and the ventral (OP1 and OP4) sensorimotor stream

International audience; We evaluated the effect of normal aging on the inter-hemispheric processing of semantic information by using the divided visual field (DVF) method, with words and pictures. Two main theoretical models have been considered, (a) the HAROLD model which posits that aging is associated with supplementary recruitment of the right hemisphere (RH) and decreased hemispheric specialization, and (b) the RH decline theory, which assumes that the RH becomes less efficient with aging, associated with increased LH specialization. Two groups of subjects were examined, a Young Group (YG) and an Old Group (OG), while participants performed a semantic categorization task (living vs. non-living) in words and pictures. The DVF was realized in two steps: (a) unilateral DVF presentation with stimuli presented separately in each visual field, left or right, allowing for their initial processing by only one hemisphere, right or left, respectively; (b) bilateral DVF presentation (BVF) with stimuli presented simultaneously in both visual fields, followed by their processing by both hemispheres. These two types of presentation permitted the evaluation of two main characteristics of the inter-hemispheric processing of information, the hemispheric specialization (HS) and the inter-hemispheric cooperation (IHC). Moreover, the BVF allowed determining the driver-hemisphere for processing information presented in BVF. Results obtained in OG indicated that: (a) semantic categorization was performed as accurately as YG, even if more slowly, (b) a non-semantic RH decline was observed, and (c) the LH controls the semantic processing during the BVF, suggesting an increased role of the LH in aging. However, despite the stronger involvement of the LH in OG, the RH is not completely devoid of semantic abilities. As discussed in the paper, neither the HAROLD nor the RH decline does fully explain this pattern of results. We rather suggest that the effect of aging on the hemispheric specialization and inter-hemispheric cooperation during semantic processing is explained not by only one model, but by an interaction between several complementary mechanisms and models.

L’ischemia cerebrale (IC) rappresenta l’80% degli accidenti vascolari cerebrali (AVC), seconda causa di mortalita nel mondo. Essa fa seguito all’interruzione del flusso ematico in un’arteria cerebrale. Si definisce come una riduzione della pressione di perfusione cerebrale sotto la soglia di autoregolazione fisiologica del flusso ematico cerebrale, che conduce a un insufficiente apporto in ossigeno e in energia. Si tratta di un fenomeno che evolve molto rapidamente nel tempo e nello spazio, andando dal «silenzio elettrofisiologico» di neuroni ancora vitali (penombra) alla necrosi irreversibile (infarto). La risonanza magnetica o la TC di perfusione permettono di visualizzare in urgenza queste zone di IC. I meccanismi che inducono la morte cellulare (omeostasi di Ca2+, Na+/Cl–, K+ ed eccitotossicita, depolarizzazione peri-infartuale, stress ossidativo, infiammazione, ecc.) non sono limitati ai neuroni. Essi coinvolgono l’insieme dell’unita neurovascolare, gli oligodendrociti e la microglia. Inoltre, l’immunodepressione sistemica causata dall’AVC e responsabile di infezioni che peggiorano la prognosi funzionale. E necessaria una migliore comprensione integrativa «al di la del neurone» di questi fenomeni per sviluppare dei trattamenti limitati, a tutt’oggi, alla gestione specializzata delle AVC, alla riperfusione per trombolisi e all’emicraniectomia decompressiva per gli infarti estesi. Parallelamente ai meccanismi deleteri, esistono una neuroprotezione endogena iniziale e, poi, un recupero che dura diversi mesi. Questo recupero, facilitato dalla rieducazione, e legato a un compenso dei deficit e alla plasticita cerebrale: riorganizzazione dei circuiti danneggiati e neurosinaptogenesi in relazione con la glia e i microvasi all’interno di «nicchie neuro-oligo-vascolari» perilesionali. L’ottimizzazione di questa plasticita multicellulare e, oggi, l’obiettivo di trattamenti promettenti di medicina rigenerativa basati sull’utilizzo di fattori di crescita e di cellule staminali o differenziate (terapia cellulare).

Introduction/Background The sense of verticality results from a complex multisensory integration suggesting the existence of internal models of verticality perception. Recent data from our team suggest that the parietal operculum, the posterior insula and the posterior-lateral thalamus, in the right hemisphere, constitute the core polymodal regions that construct and update the internal models of verticality. The aim of this study was double. First, to analyse functional connectivity, in a group of healthy participants, of the three core regions in a larger verticality perception network, established on literature data. Second, to analyse functional connectivity of these three regions in a group of stroke patients presenting an altered perception of verticality. Material and method Functional connectivity was studied using ROI-to-ROI method in Connectivity toolbox with resting state functional Magnetic Resonance Imaging (fMRI). The regions of interest were selected from Anatomy toolbox, with source regions OP1, OP2, Ig1, Ig2, parietal and somatosensory thalamus. The first study concerned 74 healthy participants and the second study concerned 5 stroke patients with altered verticality perception in visual modality. Results In the healthy participants group, the three regions (represented by OP1, OP2, Ig1, Ig2, ThP and ThS) constitute a highly connected network in both hemispheres. In stroke patients group, this network was globally preserved in the healthy hemisphere, but disrupted in the brain-damaged hemisphere. Moreover, we observed a correlation between the loss of inter-hemispheric connectivity within this network and the altered perception of verticality in the visual modality. Conclusion The parietal operculum, the posterior insula and the posterior-lateral thalamus form a network that could correspond to the ‘sense of upright’ network.

In the last decade, functional MRI (fMRI) has become one of the most widely used functional imaging technique in neurosciences. However, its clinical applications remain limited. Despite methodological and practical issues, fMRI data has been validated by different techniques (magnetoencephalography, Wada test, electrical and magnetic stimulations, and surgical resections). In neurosurgical practice, fMRI can identify eloquent areas involved in motor and language functions, and may evaluate characteristics of postoperative neurological deficit including its occurrence, clinical presentation and duration. This may help to inform patients and to prepare postoperative care. fMRI may also identify epileptic foci. In neurological practice, fMRI may help to determine prognosis of recovery after stroke, appropriate medication, and rehabilitation. fMRI may help to identify patients at risk of developing Alzheimer disease. Finally, cerebrovascular reactivity imaging is an interesting approach that might provide new radiological insights of vascular function.

Resume L’hypoglycemie est une cause de coma frequente et grave. Les indicateurs du pronostic, telles la severite de l’hypoglycemie et la duree du coma, sont peu nombreux et leur fiabilite est incertaine. Nous rapportons un cas de coma hypoglycemique associe a la presence d’hypersignaux en IRM de diffusion, suivie de l’installation rapide d’une atrophie cerebrale au niveau des memes aires. Ces constatations suggerent que l’IRM de diffusion serait un marqueur des lesions neuronales dans l’hypoglycemie et pourrait constituer un indicateur du pronostic.

International audience; ObjectiveTo assess the efficiency of Visual Feedback (VF) on language recovery and plasticity in three chronic non-fluent aphasic patients. VF is based on language-action interaction, thus, language skills are improved by rehabilitation strategies based on execution and observation of motor actions. VF is an ultrasound system coupled with video images, allowing patients to ‘see their own lips and tongue at work’ during speech and improve their awareness of their lingual and labial movements and their ability to coordinate and combine phonemes and syllables. Brain plasticity was explored with functional MRI.Material/Patients and methods– Control group tested with functional MRI to identify language networks underlying three tasks of interest;– three patients with non-fluent chronic aphasia after ischemic stroke, were examined in neuropsychology, speech therapy, acoustics and fMRI, before and after VF. VF has been applied during 14 sessions (2 weeks, 1 per day). The performance was evaluated before and after VF. In fMRI, specific comparisons were performed to identify: – patterns of reorganization reflecting spontaneous neuro-plasticity, – the effect of VF on speech recovery and language plasticity.ResultsAfter 14 sessions of VF, acoustic analyses showed a more canonical vowel production and better repetition of consonants. Speech analysis for repetition of syllables, naming and rhytme judgment, showed a general improvement of performances, variable among patients. In terms of cerebral activation, various patterns of language reorganization were obtained according to task and level of language recovery. A general trend can be identified with the improvement of language performance after VF, which is a right hemispheric predominance before VF, followed by a return of the activity to the left hemisphere, after VF.Discussion - ConclusionResults are discussed according to current models of inter and intra-hemispheric reorganization of language.

Introduction L’efficacite du facteur VII recombinant dans les hematomes cerebraux primitifs a recemment ete rapportee dans une etude de phase IIb, alors qu’il n’existait jusqu’alors aucune therapeutique specifique pour cette pathologie. Objectifs Evaluer en pratique clinique dans une unite neurovasculaire (UNV) la tolerance du facteur VII recombinant (FVIIr) chez des patients admis pour un hematome cerebral primitif. Methodes Les patients inclus etaient ceux admis dans l’UNV du CHU de Grenoble a partir de l’astreinte neurovasculaire pour un hematome primitif, repondant aux criteres d’inclusion de l’etude de Mayer et al, entre janvier 2005 et decembre 2006. Le traitement par FVIIr a ete administre dans les conditions de l’etude (delai Resultats 26 patients (âge moyen 59,2 ans) repondaient aux criteres d’inclusion. 12 ont recu un traitement par FVIIr. Le score NIHSS moyen a l’admission etait de 15,1 pour le groupe traite versus 15 pour le groupe non traite (p = 0,98). Le score NIHSS a la sortie etait de 10 pour le groupe traite contre 16,29 pour le groupe non traite (p = 0,18). 3 patients traites (25 p. 100) ont presente une complication thromboembolique veineuse versus 2 patients (14 p. 100) non traites (p = 0,42). Aucune complication arterielle n’est survenue. Discussion La difference de tolerance chez les patients traites par FVIIr n’est pas statistiquement significative. On remarque neanmoins pour 2 patients traites la survenue d’une complication thromboembolique veineuse moins de 48 h apres le debut des troubles. L’amelioration evaluee par le score NIHSS a la sortie des patients traites n’est pas non plus significative. Les resultats a 3 mois, non encore disponibles, seront presentes. Conclusion L’administration du FVIIr dans l’hematome cerebral de moins de 4 heures est bien toleree, mais pourrait exposer a un risque maladie thromboembolique veineuse precoce.