To study the BOLD effect numerically, blood vessels are often modelled as infinite cylinders [1] (infinite cylinder model, ICM). To simplify analytical calculations, signal dephasing resulting from spins diffusing around these infinite cylinders is then usually further approximated as a mono-exponential signal decay as suggested by Ogawa et al.[1]. Although for a wide range of parameters this m...

PURPOSE The magnocellular and parvocellular pathways (M and P pathways) are the major pathways of the visual system, with distinct histologic and physiologic properties that may also have different metabolic characteristics. We hypothesize that the differences of the 2 visual pathways would also manifest as differences in the signal time course of blood oxygen level-dependent functional MR imag...

The present case demonstrates that the blood oxygenation level-dependent (BOLD) signal intensity can decrease in the activated motor cortex on the lesion side (left) of a patient with a left frontal glioma during functional recovery after surgery. Near-infrared spectroscopy revealed that the decrease of BOLD signal was associated with increases of cerebral blood volume and deoxyhemoglobin conce...

Functional MRI (fMRI) using the blood oxygenation level dependent (BOLD) signal is a common technique in the study of brain function. The BOLD signal is sensitive to the complex interaction of physiological changes including cerebral blood flow (CBF), cerebral blood volume (CBV), and cerebral oxygen metabolism (CMRO2). A primary goal of quantitative fMRI methods is to combine BOLD imaging with ...

Introduction The need exists for a functional MRI (fMRI) technique capable of artifact-free whole brain coverage, with good blood oxygenation level dependent (BOLD) contrast to noise ratio (CNR), and high temporal resolution. Conventional gradient echo (GRE) BOLD fMRI suffers from signal dropout in regions of magnetic field inhomogeneity, limiting coverage, while spin echo fMRI has reduced BOLD...

The spatiotemporal characteristics of the hemodynamic response to increased neural activity were investigated at the level of individual intracortical vessels using BOLD-fMRI in a well-established rodent model of somatosensory stimulation at 11.7 T. Functional maps of the rat barrel cortex were obtained at 150 × 150 × 500 μm spatial resolution every 200 ms. The high spatial resolution allowed s...

Blood-oxygen-level-dependent magnetic resonance imaging (BOLD MRI) has the potential to quantify skeletal muscle oxygenation with high temporal and high spatial resolution. The purpose of this study was to characterize skeletal muscle BOLD responses during steady-state plantar flexion exercise (i.e., during the brief rest periods between muscle contraction). We used three different imaging moda...

Functional magnetic resonance imaging blood-oxygenation-level-dependent (fMRI-BOLD) signal representing neural activity may be optimized by discriminating MR signal components related to neural activity and those related to intrinsic properties of the cortical vasculature. The objective of this study was to reduce the hemodynamic change independent of neural activity to obtain a scaled fMRI-BOL...

The functional magnetic resonance imaging (fMRI) blood oxygenation level-dependent (BOLD) signal is regularly used to assign neuronal activity to cognitive function. Recent analyses have shown that the local field potential (LFP) gamma power is a better predictor of the fMRI BOLD signal than spiking activity. However, LFP gamma power and spiking activity are usually correlated, clouding the ana...

1Department of Optical Engineering, State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou 310027, China 2B. Thomas Golisano College of Computing and Information Sciences, Rochester Institute of Technology, Rochester, NY 14623, USA 3Department of Radiology, Tongji Hospital of Tongji University, Shanghai 200065, China 4University of Rochester Medical Center, Roches...