Featured Articles

  • Sparse EEG Source Localization Using LAPPS: Least Absolute l -P (0 < p < 1) Penalized Solution

    Electroencephalographic (EEG) is commonly used to study the brain activity with high temporal resolution, but it is usually inevitably contaminated by strong outliers. Here, we propose a novel EEG source localization algorithm, LAPPS, which employs the l 1-loss for the residual error to alleviate the effect of outliers and another l p-penalty norm (p=0.5) to obtain sparse sources while suppressing Gaussian noise in EEG recordings. The simulation results in various dipoles configurations under various SNRs prove the superiority of LAPPS. In a real visual oddball experiment, LAPPS also obtained sparse activations consistent with previous findings revealed by EEG and fMRI.

  • Electrophysiological Brain Connectivity: Theory and Implementation

    Electrophysiological Brain Connectivity: Theory and Implementation

    In this tutorial paper, we describe the theoretical basis, computational algorithms, and applications of dynamic functional brain connectivity analysis from electromagnetic measurements, including electroencephalography (EEG), magnetoencephalography (MEG), electrocorticography (ECoG), and stereoelectroencephalography (SEEG). Various connectivity estimators are discussed, and algorithms introduced. The merits, limitations, and needs for future development are also discussed. The tutorial will serve both new comers and practitioners working on brain connectivity analysis.

  • Real-time Temperature Measurements of HMEC-1 Cells during Inflammation Production and Repair detected by Wireless Thermometry

    Real-time Temperature Measurements of HMEC-1 Cells during Inflammation Production and Repair detected by Wireless Thermometry

    Cell inflammation and its repair process are extremely important for inflammation treatment. The processes can be reflected through real-time in situ cellular temperature changes. By detecting the HMEC-1 cellular temperature under lipopolysaccharide inflammation production and norepinephrine for inflammation repair, combining the changes in cell viability, inflammatory factor levels and ATP content caused by different lipopolysaccharide or norepinephrine doses, an obvious inflammatory response and repair effect was obtained. Temperature variations were correlated with ATP content. The relationship between cell thermogenesis and intracellular energy reserves is related to cell processes. Analysis of the energy changes in different physiological process can be realized.

  • Reference-Based Integral MR-EPT: Simulation and Experiment Studies at 9.4T MRI

    Magnetic resonance electrical properties tomography (MR-EPT) is an emerging technology which plays an important role in specific absorption rate monitoring. The current integral-equation (IE) based MR-EPT methods utilize simulated incident radio-frequency (RF) fields, which are inaccurate and lead to reconstruction errors. In this work, the incident field approximation (IFA) is first demonstrated. IFA utilizes a reference subject and RF field mapping techniques to map the incident field, hence the loading effect of the RF coil can be involved in the IE-based MR-EPT. This method may push the IE-based MR-EPT into practical utilization at UHF-MRI systems.

  • Encapsulation Approaches for In-Stent Wireless Magnetoelastic Sensors

    Wireless magnetoelastic sensors are capable of measuring biomass accumulation within stents. One major challenge for these sensors is designing suitable encapsulation that protects the sensor during rigorous minimally-invasive deployment while also retaining its ability to sense the biomass. This paper describes two polymer-based package designs that meet these requirements using different compromises for the mechanical stiffness of the stent; both a flexible and a stiff encapsulation design allow the sensors to survive bending with a radius of curvature as small as 3 cm. In situ tests performed on the flexible design show a wireless range of ≈10 cm.

  • A Single-Scan Inhomogeneity-Tolerant NMR Method

    A Single-Scan Inhomogeneity-Tolerant NMR Method for High-Resolution 2D J-Resolved Spectroscopy

    2D homonuclear J-resolved NMR spectroscopy has been widely applied to molecular conformational elucidation, metabolite analysis and in vivo study. However, conventional 2D J-resolved experiments generally suffer from two intrinsic issues, namely long acquisition duration and magnetic field inhomogeneity. Herein, a general single-scan NMR method, SGEN-J, is proposed to address aforementioned two crucial issues, thus applicable to rapidly detecting biological tissues with intrinsic susceptibility variations and abundant metabolites. Experiments of SGEN-J on various chemical and biological samples were performed to demonstrate its feasibility and effectiveness for molecular structure elucidation, biomedical study, even potential in vivo study.

  • Micro-coil design influences the spatial extent of responses to intracortical magnetic stimulation

    Micro-coil Design Influences the Spatial Extent of Responses to Intracortical Magnetic Stimulation

    Magnetic stimulation from micro-coils has the potential to improve the spatial resolution of cortical stimulation by selectively activating pyramidal neurons while avoiding passing axons. Here, we explored how micro-coil design influences the effectiveness and selectivity with which neurons are activated. Computational modeling and physiological experiments revealed that the use of a sharp bend at the coil tip (V-shaped) enhanced coil selectivity; an additional bend provided even higher selectivity. The use of a second loop enhanced coil strength. Our results suggest that further optimization of coil design may help to enhance both the strength and selectivity of future coil designs.

  • In vivo Visualization of Vasculature in Adult Zebrafish by High Frequency Ultrafast Ultrasound Imaging

    In vivo Visualization of Vasculature in Adult Zebrafish by using High-Frequency Ultrafast Ultrasound Imaging

    Zebrafish has recently become a crucial animal model for studying human diseases. However, when a zebrafish matures completely, its body loses transparency, making conventional optical imaging techniques difficult for visualizing the vessels. In the present study, high-frequency (40-MHz) micro-Doppler imaging (HFμDI) based on ultrafast ultrasound imaging was proposed for adult zebrafish dorsal vascular mapping in vivo. Blood flow signals were extracted using an eigen-based clutter filter. Blood vessels were clearly observed in 2D and 3D HFμDI. The minimal diameter of vessel can be detected was 36 μm. The maximum flow velocity range was approximately 3–4 mm/s on the dorsal vessels.

  • A Machine Learning Shock Decision Algorithm for use during Piston-driven Chest Compressions

    A Machine Learning Shock Decision Algorithm for use during Piston-driven Chest Compressions

    Cardiopulmonary resuscitation (CPR) therapy provides oxygen to the vital organs during cardiac arrest. An accurate heart rhythm analysis during piston-driven mechanical chest compressions would avoid interruptions in CPR therapy. We developed a rhythm analysis algorithm that combines adaptive filtering to remove compression artifacts from the electrocardiogram, multiresolution stationary wavelet transform (SWT) analysis for feature extraction, and a gaussian support vector machine (SVM) classifier for the shock/no-shock decision. Our results show that the heart rhythm can be accurately diagnosed during mechanical compressions, avoiding interruptions in CPR that compromise perfusion of the vital organs.

  • Adaptive and Wireless Recordings of Electrophysiological Signals during Concurrent Magnetic Resonance Imaging

    Adaptive and Wireless Recordings of Electrophysiological Signals during Concurrent Magnetic Resonance Imaging

    Strong electromagnetic fields during functional magnetic resonance imaging (fMRI) presents a challenging environment for concurrent electrophysiological recordings. Here, we present a miniaturized, wireless platform – “MR-Link”, that provides a hardware solution for simultaneous electrophysiological and fMRI signal acquisition. By detecting changes in the electromagnetic field during fMRI the device synchronizes amplification and sampling of biopotentials. Then, it wirelessly transmits the recorded data to the MR-receiver coil. MR-Link offers an inexpensive solution by eliminating the need for bulky amplifiers, high-speed sampling, additional storage or synchronization hardware. Thus, the technology is expected to open new avenues for widely accessible, integrative neuroimaging tools.

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