A5086166149- Advanced MRI Techniques and Applications
- Neurological disorders and treatments
- Neuroscience and Neural Engineering
- Functional Brain Connectivity Studies
- EEG and Brain-Computer Interfaces
- Neural dynamics and brain function
- Transcranial Magnetic Stimulation Studies
- Visual perception and processing mechanisms
- Atomic and Subatomic Physics Research
- Electrical and Bioimpedance Tomography
- Ultrasound and Hyperthermia Applications
- Advanced Memory and Neural Computing
- Muscle activation and electromyography studies
- Cardiac pacing and defibrillation studies
- Cardiac Arrhythmias and Treatments
- Vagus Nerve Stimulation Research
- Optical Imaging and Spectroscopy Techniques
- Sleep and Wakefulness Research
- Neuroscience and Music Perception
- Advanced Neuroimaging Techniques and Applications
- CCD and CMOS Imaging Sensors
- Pain Management and Treatment
- Photoreceptor and optogenetics research
- Advanced Vision and Imaging
- Parkinson's Disease Mechanisms and Treatments
Athinoula A. Martinos Center for Biomedical Imaging
2015-2024
Harvard University
2015-2024
Massachusetts General Hospital
2015-2024
National Institute of Mental Health
2024
Boston Children's Hospital
2023-2024
St. Michael's Hospital
2024
NanoScale Corporation (United States)
2021
Morpho (United States)
2015
Harvard–MIT Division of Health Sciences and Technology
2008
Massachusetts Institute of Technology
2004-2008
Sleep is essential for both cognition and maintenance of healthy brain function. Slow waves in neural activity contribute to memory consolidation, whereas cerebrospinal fluid (CSF) clears metabolic waste products from the brain. Whether these two processes are related not known. We used accelerated neuroimaging measure physiological dynamics human discovered a coherent pattern oscillating electrophysiological, hemodynamic, CSF that appears during non-rapid eye movement sleep. Neural slow...
Life or death in hostile environments depends crucially on one's ability to detect and gate novel sounds awareness, such as that of a twig cracking under the paw stalking predator noisy jungle. Two distinct auditory cortex processes have been thought underlie this phenomenon: (i) attenuation so-called N1 response with repeated stimulation (ii) elicitation mismatch negativity (MMN) by changes repetitive aspects stimulation. This division has based previous studies suggesting that, unlike for...
Human neuroimaging studies suggest that localization and identification of relevant auditory objects are accomplished via parallel parietal-to-lateral-prefrontal “where” anterior-temporal-to-inferior-frontal “what” pathways, respectively. Using combined hemodynamic (functional MRI) electromagnetic (magnetoencephalography) measurements, we investigated whether such dual pathways exist already in the human nonprimary cortex, as suggested by animal models, selective attention facilitates sound...
The frontal eye field (FEF) is one of several cortical regions thought to modulate sensory inputs. Moreover, hypotheses suggest that the FEF can only early visual areas in presence a stimulus. To test for bottom-up gating signals, we microstimulated subregions two monkeys and measured effects throughout brain with functional magnetic resonance imaging. activity higher-order was strongly modulated by stimulation, independent stimulation. In contrast, stimulation induced topographically...
Electrical stimulation is currently used to treat a wide range of cardiovascular, sensory and neurological diseases. Despite its success, there are significant limitations application, including incompatibility with magnetic resonance imaging, limited control electric fields decreased performance associated tissue inflammation. Magnetic overcomes these but existing devices (that is, transcranial stimulation) large, reducing their translation chronic applications. In addition, not effective...
Purpose MRI may cause brain tissue around deep stimulation (DBS) electrodes to become excessively hot, causing lesions. The presence of extracranial loops in the DBS lead trajectory has been shown affect specific absorption rate (SAR) radiofrequency energy at electrode tip, but experimental studies have reported controversial results. goal this study was perform a systematic numerical provide better understanding effects leads on local SAR during 64 and 127 MHz. Methods A total 160...
Awakening from sleep reflects a profound transformation in neural activity and behavior. The thalamus is key controller of arousal state, but whether its diverse nuclei exhibit coordinated or distinct at transitions behavioral state unknown. Using fast fMRI ultra-high field (7 Tesla), we measured sub-second across thalamocortical networks within nine thalamic to delineate these dynamics during spontaneous state. We discovered stereotyped sequence cingulate cortex that preceded after period...
WE present the first simultaneous measurements of evoked potentials (EPs) and fMRI hemodynamic responses to visual stimulation. Visual (VEPs) were recorded both inside outside static 3 T magnetic field, during examination. We designed, constructed, tested a non-magnetic 64-channel EEG recording cap. By using large number channels it is possible design spatial filter capable removing artifact noise when EEG/EPs within strong field. show that designed recovering ballistocardiogram-contaminated...
Purpose MRI of patients with deep brain stimulation (DBS) implants is strictly limited due to safety concerns, including high levels local specific absorption rate (SAR) radiofrequency (RF) fields near the implant and related RF-induced heating. This study demonstrates feasibility using a rotating linearly polarized birdcage transmitter 32-channel close-fit receive array significantly reduce SAR in DBS patients. Methods Electromagnetic simulations phantom experiments were performed generic...
Clinical electrical stimulation systems--such as pacemakers and deep brain stimulators (DBS)--are an increasingly common therapeutic option to treat a large range of medical conditions. Despite their remarkable success, one the significant limitations these devices is limited compatibility with magnetic resonance imaging (MRI), standard diagnostic tool in medicine. During MRI exam, leads used devices, implanted body patient, act electric antenna potentially causing amount energy be absorbed...
Abstract Patients with deep brain stimulation (DBS) implants may be subject to heating during MRI due interaction excitatory radiofrequency (RF) fields. Parallel RF transmit (pTx) has been proposed minimize such RF-induced in preliminary proof-of-concept studies. The present work evaluates the efficacy of pTx technique on realistic lead trajectories obtained from nine DBS patients. Electromagnetic simulations were performed using 4- and 8-element coils compared a standard birdcage coil...
Patients with implanted medical devices such as deep brain stimulation or spinal cord are often unable to receive magnetic resonance imaging (MRI). This is because, once the device within radio frequency (RF) field of MRI scanner, electrically conductive leads act antenna, amplifying RF energy deposition in tissue and causing possible excessive heating. Here, we propose a novel concept lead design which 40-cm wires coated ~1.2-mm layer high dielectric constant material (155 <; ε <sub...
Abstract Purpose To investigate the behavior of whole‐head and local specific absorption rate (SAR) as a function trajectory acceleration factor target excitation pattern due to parallel transmission (pTX) spatially tailored excitations at 7T. Materials Methods Finite‐difference time domain (FDTD) simulations in multitissue head model were used obtain B 1 + electric field maps an eight‐channel transmit array. Local average SAR produced by 2D‐spiral‐trajectory examined factor, R , variety...
Purpose To evaluate the local specific absorption rate (SAR) and heating around retained cardiac leads during MRI at 64 MHz (1.5T) 127 (3T) as a function of RF coil type imaging landmark. Methods Numerical models were built from CT X‐ray images 6 patients with leads. Electromagnetic simulations bio‐heat modeling performed body head coils tuned to positioned 9 different landmarks covering an area lower limbs. Results For all both 1.5T 3T, transmit produced negligible temperature rise ( ) for...
Abstract The purpose of this study was to investigate the changes in specific absorption rate (SAR) human‐head tissues while using nonmagnetic metallic electroencephalography (EEG) electrodes and leads during magnetic resonance imaging (MRI). A realistic, high resolution (1 mm 3 ) head model from individual MRI data adopted describe accurately thin tissues, such as bone marrow skin. RF power dissipated human evaluated FDTD algorithm. Both surface bird cage coils were used. following numbers...