Alexandre Krainik

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Examination of functional interactions through effective connectivity requires the determination of three distinct levels of information: (1) the regions involved in the process and forming the spatial support of the network, (2) the presence or absence of interactions between each pair of regions, and (3) the directionality of the existing interactions.(More)
Studies in non-human primates have shown that medial premotor projections to the striatum are characterized as a set of distinct circuits conveying different type of information. This study assesses the anatomical projections from the supplementary motor area (SMA), pre-SMA and motor cortex (MC) to the human striatum using diffusion tensor imaging (DTI)(More)
OBJECTIVE To determine the compensatory mechanisms involved in the recovery of motor function following surgical lesions of the supplementary motor area (SMA) and their relation to the clinical characteristics of recovery. SUBJECTS AND METHODS Twelve patients were referred for surgery of low-grade gliomas located in the SMA, and compared to eight healthy(More)
Interictal diffusion imaging studies in patients with medial temporal lobe epilepsy (MTLE) accompanied by hippocampal sclerosis (HS) have shown an increased diffusivity in the epileptogenic hippocampus. In this study, we wanted to explore the whole brain in order to determine if MTLE could have an impact on the organization and the architecture of a large(More)
BACKGROUND AND PURPOSE Comparative studies across populations using functional magnetic resonance imaging (fMRI) rely on a similar relationship between blood oxygen level-dependent (BOLD) signal and neural activity. However, in elderly and patients with cerebrovascular disease, impaired cerebrovascular dynamics and neurovascular coupling may explain(More)
In electroencephalographic (EEG) measurements performed during functional Magnetic Resonance Imaging (fMRI), imaging and cardiac artefacts strongly contaminate the EEG signal. Several algorithms have been proposed to suppress these artefacts and most of them have shown important improvements with respect to uncorrected signals. However, the relative(More)
Because of its reversibility and adaptability, deep brain stimulation (DBS) has recently gained interest in psychiatric disorders, such as obsessive-compulsive disorders (OCD) and depression. In OCD, DBS is now an alternative procedure to lesions of fascicles such as the anterior capsule, which links the orbitofrontal cortex, the cingulum, and the thalamus,(More)
OBJECTIVE To explore the selectivity of neuronal somatotopic representation in the striatum of patients with unilateral task-specific dystonia of the right arm. MATERIALS AND METHODS The authors used fMRI in 14 right-handed dystonic subjects to examine putaminal organization. Subjects performed flexion/extension of the right and left fingers and toes, and(More)
Because of the great diversity of clinical features, its unforeseeable evolution, and a small proportion of cases that will worsen in the acute phase, cerebral venous thrombosis must be diagnosed as early as possible so that specific treatment can be started, typically transcatheter thrombolysis or systemic anticoagulation. Unenhanced computed tomography(More)
OBJECT The aim of this study was to study the effects of MR imaging on the electrical settings of deep brain stimulation (DBS) systems and their clinical consequences. METHODS The authors studied the effects of 1.5-T MR imaging on the electrical settings of implanted DBS systems, including 1 or more monopolar or quadripolar leads, extension leads, and(More)