A5086341485- Advanced MRI Techniques and Applications
- Functional Brain Connectivity Studies
- Medical Imaging Techniques and Applications
- Neural dynamics and brain function
- Visual perception and processing mechanisms
- Medical Image Segmentation Techniques
- Advanced Neuroimaging Techniques and Applications
- MRI in cancer diagnosis
- Neural and Behavioral Psychology Studies
- Optical Imaging and Spectroscopy Techniques
- Radiomics and Machine Learning in Medical Imaging
- Face Recognition and Perception
- Neuroscience and Neuropharmacology Research
- Cerebrovascular and Carotid Artery Diseases
- EEG and Brain-Computer Interfaces
- Anatomy and Medical Technology
- Electrolyte and hormonal disorders
- Bipolar Disorder and Treatment
- Radiation Detection and Scintillator Technologies
- Pain Mechanisms and Treatments
- Ferroelectric and Negative Capacitance Devices
- Neurological disorders and treatments
- Cell Image Analysis Techniques
- Digital Image Processing Techniques
- Advanced X-ray and CT Imaging
National Institute of Mental Health
2002-2021
National Institutes of Health
2002-2021
National Institute of Mental Health
2018
Montreal Neurological Institute and Hospital
1991-2009
Max Planck Society
2006
Aarhus University Hospital
2002
McGill University
1988-2001
Massachusetts General Hospital
1998-1999
We present a unified statistical theory for assessing the significance of apparent signal observed in noisy difference images. The results are usable wide range applications, including fMRI, but discussed with particular reference to PET images which represent changes cerebral blood flow elicited by specific cognitive or sensorimotor task. Our main result is an estimate P-value local maxima Gaussian, t, chi(2) and F fields over search regions any shape size number dimensions. This unifies...
Many studies of brain function with positron emission tomography (PET) involve the interpretation a subtracted PET image, usually difference between two images under baseline and stimulation conditions. The purpose these is to see which areas are activated by condition. In many cognitive studies, activation so slight that experiment must be repeated on several subjects averaged improve signal-to-noise ratio. image then standardized have unit variance searched for local maxima. main problem...
The representation of pain in the cerebral cortex is less well understood than that any other sensory system. However, with use magnetic resonance imaging and positron emission tomography humans, it has now been demonstrated painful heat causes significant activation contralateral anterior cingulate, secondary somatosensory, primary somatosensory cortices. This contrasts predominant caused by vibrotactile stimuli similar experiments. Furthermore, unilateral cingulate indicates this forebrain...
The relationship between blood oxygenation level-dependent (BOLD) MRI signals, cerebral flow (CBF), and oxygen consumption (CMRO2) in the physiological steady state was investigated. A quantitative model, based on flow-dependent dilution of metabolically generated deoxyhemoglobin, validated by measuring BOLD signals relative CBF simultaneously primary visual cortex (V1) human subjects (N = 12) during graded hypercapnia at different levels stimulation. responses to specific conditions were...
The aim of this study was to test the hypothesis that, within a specific cortical unit, fractional changes in cerebral blood flow (CBF) and metabolic rate oxygen consumption ( CMR O 2 ) are coupled through an invariant relationship during physiological stimulation. This achieved by simultaneously measuring relative these quantities human primary visual cortex (V1) graded stimulation with patterns designed selectively activate different populations V1 neurons. Primary delineated individually...
Perceptual decision making typically entails the processing of sensory signals, formation a decision, and planning execution motor response. Although recent studies in monkeys humans have revealed possible neural mechanisms for perceptual making, much less is known about how subsequently transformed into action whether or not represented at an abstract level, i.e., independently specific To address this issue, we used functional MRI to monitor changes brain activity while human subjects...
PET images of cerebral blood flow (CBF) in an activation study are usually smoothed to a resolution much poorer than the intrinsic camera. This is done reduce noise and overcome problems caused by neuroanatomic variability among different subjects undertaking same experimental task. In many studies choice this smoothing arbitrarily fixed at about 20 mm FWHM, resulting statistical field or parametric map searched for local maxima. Poline Mazoyer [(1994): J Cereb Blood Flow Metab 14:690–699;...
Quantitative interpretation of functional images (PET or SPECT) is hampered by poor spatial resolution, low counting statistics, and, for many tracers, contrast between different brain structures interest. Furthermore, normal tracer distributions can be severely disrupted such gross pathologies as stroke, tumor, and dementia. Hence, the complementary anatomical information provided CT MRI essential accurate reproducible regional analysis data. We have developed methods simultaneous...
A procedure is described for combining anatomical information from magnetic resonance imaging (MRI) or computerized tomography (CT) and functional positron emission (PET) in a rapid fashion. MRI data are combined with the definition, storage, recall of anatomically based regions interest. An atlas standard interest, defined set 18 parallel planes spaced at 6-mm intervals, provides an initial region interest template each patient slice. Global adjustments to scale, orientation, position...
We describe the implementation, experience and preliminary results obtained with a 3-D computerized brain atlas for topographical functional analysis of sub-regions. A volume-of-interest (VOI) was produced by manual contouring on 64 adjacent 2 mm-thick MRI slices to yield 60 structures in each hemisphere which could be adjusted, originally global affine transformation or local interactive adjustments, match individual datasets. have now added non-linear deformation (warp) capability...
Repeated experience with a visual stimulus can result in improved perception of the stimulus, i.e., perceptual learning. To understand underlying neural mechanisms this process, we used functional magnetic resonance imaging to track brain activations during course training on contrast discrimination task. Based their ability improve task within single scan session, subjects were separated into two groups: "learners" and "nonlearners." As learning progressed, learners showed progressively...
The human brain coordinates a wide variety of motor activities. On large scale, the cortical system is topographically organized such that neighboring body parts are represented by areas. This homunculus-like somatotopic organization along central sulcus has been observed using neuroimaging for as face, hands and feet. However, on finer invasive electrical stimulation studies show deviations from this suggest an organizing principle based actions rather than part moved. It not clear how...
We present a unified statistical theory for assessing the significance of apparent signal observed in noisy difference images. The results are usable wide range applications, including fMRI, but discussed with particular reference to PET images which represent changes cerebral blood flow elicited by specific cognitive or sensorimotor task. Our main result is an estimate P-value local maxima Gaussian, t, χ2 and F fields over search regions any shape size number dimensions. This unifies...
The brain can be parcellated into numerous anatomical and functional subunits. classic work by Brodmann (Vergleichende Lokalisationslehre der Grosshirnrinde in ihren Prinzipien dargestellt auf Grund des Zellenbaues. Leipzig: Barth; 1909) identified areas of the cerebral cortex based on histological differences. An alternative to his cytoarchitectonic approach is myeloarchitectonic approach. MRI has excellent white/gray matter contrast due presence myelin, thus seems uniquely suited for vivo...