E. Le Bars

Cognitive Impairment and Basal Ganglia Functional Connectivity in Vascular Parkinsonism

BACKGROUND AND PURPOSE: Patients with vascular parkinsonism have higher cognitive decline and more basal ganglia lesions. We aimed to evaluate the relationship of cognitive impairment with functional connectivity between the basal ganglia and cingulate cortex in vascular parkinsonism. MATERIALS AND METHODS: Thirty patients (8 with vascular parkinsonism and 22 with Parkinson disease) and 23 controls were enrolled. The Mattis Dementia Rating Scale and the Stroop Task were used to assess cognitive decline. MR imaging examinations included T1-MPRAGE, FLAIR, and resting-state fMRI sequences. MPRAGE was segmented to obtain basal ganglia and cingulate cortex volumes. FLAIR was segmented to obtain white matter hyperintensity lesion volume. Resting-state fMRI sequences were used to compare basal ganglia functional connectivity with the cingulate cortex between patients and controls. RESULTS: Patients with vascular parkinsonism exhibited impaired attention, resistance to interference, and inhibitory control and an increased number of errors on the Stroop Task. They also had higher caudate nucleus and white matter hyperintensity lesion volumes, which were positively correlated (ρ = 0.75, P < .0001). Caudate nucleus functional connectivity with the perigenual anterior cingulate cortex was increased in patients with vascular parkinsonism compared with controls and patients with Parkinson disease, and it was positively correlated with the caudate nucleus volume (ρ = 0.44, P = .016). Caudate nucleus functional connectivity with the posterior cingulate cortex was decreased in patients with vascular parkinsonism compared with controls and negatively correlated with the number of errors on the Stroop test (ρ = −0.51, P = .0003). CONCLUSIONS: In patients with vascular parkinsonism, cognitive decline could be related to changes of caudate nucleus functional connectivity with the cingulate cortex at resting-state, which may be induced by ischemia-related remodelling.

Kinematics in the brain: unmasking motor control strategies?

In rhythmical movement performance, our brain has to sustain movement while correcting for biological noise-induced variability. Here, we explored the functional anatomy of brain networks during voluntary rhythmical elbow flexion/extension using kinematic movement regressors in fMRI analysis to verify the interest of method to address motor control in a neurological population. We found the expected systematic activation of the primary sensorimotor network that is suggested to generate the rhythmical movement. By adding the kinematic regressors to the model, we demonstrated the potential involvement of cerebellar–frontal circuits as a function of the irregularity of the variability of the movement and the primary sensory cortex in relation to the trajectory length during task execution. We suggested that different functional brain networks were related to two different aspects of rhythmical performance: rhythmicity and error control. Concerning the latter, the partitioning between more automatic control involving cerebellar–frontal circuits versus less automatic control involving the sensory cortex seemed thereby crucial for optimal performance. Our results highlight the potential of using co-registered fine-grained kinematics and fMRI measures to interpret functional MRI activations and to potentially unmask the organisation of neural correlates during motor control.

Crossed cerebellar diaschisis after awake brain surgery: Can we measure pre/post operative changes on resting state fMRI data?

Hypometabolism has been observed in the contralesional cerebellum hemisphere after various cortical lesions, and is referred as crossed cerebellar diaschisis. It is unknown whether it can be measured after awake surgery for brain diffuse low-grade glioma. Using resting state fMRI we suggest that crossed cerebellar diaschisis can be assessed postoperatively.

NR-WP-9 Apport de l’IRM dans la prise en charge des comas traumatiques

Objectifs pedagogiques Presenter les differents aspects iconographiques rencontres dans les traumatismes crâniens graves. Connaitre la signification pronostique des differentes lesions rencontrees. Discuter la place de l’IRM dans la prise en charge des traumatises crâniens. Messages a retenir L’IRM avec les sequences FLAIR, T2* et la sequence de diffusion est le meilleur examen pour juger de la charge lesionnelle et de la severite du pronostic. Les lesions axonales diffuses sont particulierement bien explorees en IRM. Les sequences fonctionnelles, dont certaines sont encore en evaluation, semblent prometteuses.

INF-WP-5 L’IRM pas a pas : un module interactif d’enseignement des bases physiques de l’IRM

Objectifs pedagogiques A partir du site internet www.e-mri.org , demontrer les avantages de l’e-learning pour : Expliquer les bases physiques de l’Imagerie par Resonance Magnetique. Developper une approche pedagogique originale et interactive. Valider l’acquisition des connaissances. Messages a retenir L’e-Learning permet de combiner textes, images et contenu interactifs (animations, videos) en les mettant a disposition sur Internet. Il est le support d’approches pedagogiques modernes et innovantes, dont peut profiter l’enseignement de l’imagerie medicale. www.e-mri.org est un site internet en acces libre qui explique de facon interactive les bases physiques de l’Imagerie par Resonance Magnetique.