Functional MRI based on blood oxygenation level-dependent (BOLD) contrast is well established as a neuroimaging technique for detecting neural activity in the cortex of the human brain. While detection and characterization of BOLD signals, as well as their electrophysiological and hemodynamic/metabolic origins, have been extensively studied in gray matter (GM), the detection and interpretation ...

convolution each of the BOLD responses with a single universal transfer function, modeled BOLD signals were generated which when differenced with the measured BOLD signals showed residual signals which were smaller than the measurement uncertainty. The root mean square (RMS) of the residual signal (left number) was compared with the averaged standard deviation (SD) of the measured data (right n...

The blood oxygenation level-dependent (BOLD) signal serves as the basis for human functional MRI (fMRI). Knowledge of the properties of the BOLD signal, such as how linear its response is to sensory stimuli, is essential for the design and interpretation of fMRI experiments. Here, we combined the cell-type and site-specific causal control provided by optogenetics and fMRI (opto-fMRI) in mice to...

BACKGROUND Blood oxygen level-dependent (BOLD) MRI reflects tissue oxygenation and may be useful for the detection of myocardial ischemia in patients with suspected coronary artery disease. METHODS AND RESULTS We studied 25 patients with stress-induced angina using a T2*-sensitive echo planar imaging sequence before and during adenosine in a single-slice approach. BOLD-MRI results were compar...

medetomidine from isoflurane) indicated dynamic changes in BOLD low-frequency power. Within the first hour of medetomidine administration, the BOLD power was highest at < 0.1 Hz, as previously observed in human resting-state studiesl. However, the power of <0.1-Hz decreased and a peak at ~0.2-Hz increased over time (Fig. 1). The 0.2-Hz peak was observed for the rest of the experiment (up to 5 h...

The most widespread measures of human brain activity are the blood-oxygen-level dependent (BOLD) signal and surface field potential. Prior studies report a variety of relationships between these signals. To develop an understanding of how to interpret these signals and the relationship between them, we developed a model of (a) neuronal population responses and (b) transformations from neuronal ...

PURPOSE Functional magnetic resonance imaging (fMRI) was used to identify areas of brain activation during absence seizures in an awake animal model. METHODS Blood-oxygenation-level-dependent (BOLD) fMRI in the brain was measured by using T2*-weighted echo planar imaging at 4.7 Tesla. BOLD imaging was performed before, during, and after absence seizure induction by using gamma-butyrolactone (...

The blood-oxygenation-level-dependent (BOLD) signal is dependent on multiple physiological factors such as cerebral blood flow (CBF), local oxygen metabolism (CMRO(2)) and cerebral blood volume (CBV). Since caffeine affects both CBF and neural activity, its effects on BOLD remain controversial. The calibrated BOLD approach is an excellent tool to study caffeine because it combines CBF and BOLD ...

The existence of the early-negative blood-oxygenation-level-dependent (BOLD) response is controversial and its practical utility for mapping brain functions with columnar spatial specificity remains questionable. To address these issues, gradient-echo BOLD fMRI studies were performed at 4.7 T and 9.4 T using the well-established orientation column model in the cat visual cortex. A robust transi...

We investigated the effect of estrogen on cocaine-induced brain activity using blood oxygen level-dependent (BOLD) magnetic resonance imaging. Ovariectomized (Ovx) rats without estrogen and Ovx rats with estrogen (Ovx+E) were given a single saline or cocaine injection (15 mg/kg, i.p.) for 5 d. After 7 d of withdrawal from injections, rats were challenged with cocaine during functional imaging. ...