12 research outputs found
Sources of Electrical Brain Activity Most Relevant to Performance of Brain-Computer Interface Based on Motor Imagery
IN SEARCH OF NEURAL MECHANISMS OF MIRROR NEURON DYSFUNCTION IN SCHIZOPHRENIA: RESTING STATE FUNCTIONAL CONNECTIVITY APPROACH
It has been repeatedly shown that schizophrenia patients have immense alterations in goal-directed behaviour, social cognition,
and social interactions, cognitive abilities that are presumably driven by the mirror neurons system (MNS). However, the neural
bases of these deficits still remain unclear. Along with the task-related fMRI and EEG research tapping into the mirror neuron
system, the characteristics of the resting state activity in the particular areas that encompass mirror neurons might be of interest as
they obviously determine the baseline of the neuronal activity. Using resting state fMRI, we investigated resting state functional
connectivity (FC) in four predefined brain structures, ROIs (inferior frontal gyrus, superior parietal lobule, premotor cortex and
superior temporal gyrus), known for their mirror neurons activity, in 12 patients with first psychotic episode and 12 matched healthy
individuals. As a specific hypothesis, based on the knowledge of the anatomical inputs of thalamus to all preselected ROIs, we have
investigated the FC between thalamus and the ROIs. Of all ROIs included, seed-to-voxel connectivity analysis revealed significantly
decreased FC only in left posterior superior temporal gyrus (STG) and the areas in visual cortex and cerebellum in patients as
compared to controls. Using ROI-to-ROI analysis (thalamus and selected ROIs), we have found an increased FC of STG and
bilateral thalamus whereas the FC of these areas was decreased in controls. Our results suggest that: (1) schizophrenia patients
exhibit FC of STG which corresponds to the previously reported changes of superior temporal gyrus in schizophrenia and might
contribute to the disturbances of specific functions, such as emotional processing or spatial awareness; (2) as the thalamus plays a
pivotal role in the sensory gating, providing the filtering of the redundant stimulation, the observed hyperconnectivity between the
thalami and the STGs in patients with schizophrenia might explain the sequential overload with sensory inputs that leads to the
abnormal cognitive processing
Cardiac displacement tracking with data assimilation combining a biomechanical model and an automatic contour detection
International audienceData assimilation in computational models represents an essential step in building patient-specific simulations. This work aims at circumventing one major bottleneck in the practical use of data assimilation strategies in cardiac applications, namely, the difficulty of formulating and effectively computing adequate data-fitting term for cardiac imaging such as cine MRI. We here provide a proof-of-concept study of data assimilation based on automatic contour detection. The tissue motion simulated by the data assimilation framework is then assessed with displacements extracted from tagged MRI in six subjects, and the results illustrate the performance of the proposed method, including for circumferential displacements, which are not well extracted from cine MRI alone
The Parietal Atrophy Score on Brain Magnetic Resonance Imaging is a Reliable Visual Scale
IN SEARCH OF NEURAL MECHANISMS OF MIRROR NEURON DYSFUNCTION IN SCHIZOPHRENIA: RESTING STATE FUNCTIONAL CONNECTIVITY APPROACH
It has been repeatedly shown that schizophrenia patients have immense alterations in goal-directed behaviour, social cognition,
and social interactions, cognitive abilities that are presumably driven by the mirror neurons system (MNS). However, the neural
bases of these deficits still remain unclear. Along with the task-related fMRI and EEG research tapping into the mirror neuron
system, the characteristics of the resting state activity in the particular areas that encompass mirror neurons might be of interest as
they obviously determine the baseline of the neuronal activity. Using resting state fMRI, we investigated resting state functional
connectivity (FC) in four predefined brain structures, ROIs (inferior frontal gyrus, superior parietal lobule, premotor cortex and
superior temporal gyrus), known for their mirror neurons activity, in 12 patients with first psychotic episode and 12 matched healthy
individuals. As a specific hypothesis, based on the knowledge of the anatomical inputs of thalamus to all preselected ROIs, we have
investigated the FC between thalamus and the ROIs. Of all ROIs included, seed-to-voxel connectivity analysis revealed significantly
decreased FC only in left posterior superior temporal gyrus (STG) and the areas in visual cortex and cerebellum in patients as
compared to controls. Using ROI-to-ROI analysis (thalamus and selected ROIs), we have found an increased FC of STG and
bilateral thalamus whereas the FC of these areas was decreased in controls. Our results suggest that: (1) schizophrenia patients
exhibit FC of STG which corresponds to the previously reported changes of superior temporal gyrus in schizophrenia and might
contribute to the disturbances of specific functions, such as emotional processing or spatial awareness; (2) as the thalamus plays a
pivotal role in the sensory gating, providing the filtering of the redundant stimulation, the observed hyperconnectivity between the
thalami and the STGs in patients with schizophrenia might explain the sequential overload with sensory inputs that leads to the
abnormal cognitive processing
HARP-I: A Harmonic Phase Interpolation Method for the Estimation of Motion from Tagged MR Images
International audienceWe proposed a novel method called HARP-I, which enhances the estimation of motion from tagged Magnetic Resonance Imaging (MRI). The harmonic phase of the images is unwrapped and treated as noisy measurements of reference coordinates on a deformed domain, obtaining motion with high accuracy using Radial Basis Functions interpolations. Results were compared against Shortest Path HARP Refinement (SP-HR) and Sine-wave Modeling (SinMod), two harmonic image-based techniques for motion estimation from tagged images. HARP-I showed a favorable similarity with both methods under noise-free conditions, whereas a more robust performance was found in the presence of noise. Cardiac strain was better estimated using HARP-I at almost any motion level, giving strain maps with less artifacts. Additionally, HARP-I showed better temporal consistency as a new method was developed to fix phase jumps between frames. In conclusion, HARP-I showed to be a robust method for the estimation of motion and strain under ideal and non-ideal conditions