Songbirds have been evolved into models of choice for the study of the cerebral underpinnings of vocal communication. Nevertheless, there is still a need for in vivo methods allowing the real-time monitoring of brain activity. Functional Magnetic Resonance Imaging (fMRI) has been applied in anesthetized intact songbirds. It relies on blood oxygen level-dependent (BOLD) contrast revealing hemody...

Functional magnetic resonance imaging (fMRI) with blood-oxygenation level dependent (BOLD) contrast is an important tool for mapping brain activity. Interest in quantitative fMRI has renewed awareness in importance of oxidative neuroenergetics, as reflected by cerebral metabolic rate of oxygen consumption(CMRO2), for supporting brain function. Relationships between BOLD signal and the underlyin...

Introduction The baseline fMRI signal and the blood oxygenation level-dependent (BOLD) signal amplitude are not a quantitative reflection of neuronal activity as physiological and physical parameters (e.g. baseline CBF, echo time, coil sensitivity ...) contribute to the the signal. One goal of quantitative fMRI is to determine oxygen metabolism (CMRO2) from fMRI data. To this end, a calibrated ...

The blood oxygen level dependent (BOLD) signal evoked by brief neural stimulation, the hemodynamic response function (HRF), is a critical feature of neurovascular coupling. The HRF is directly related to local transient changes in oxygen supplied by cerebral blood flow (CBF) and oxygen demand, the cerebral metabolic rate of oxygen (CMRO2). Previous efforts to explain the HRF have relied upon th...

The magnitude of the blood oxygenation level-dependent (BOLD) signal depends on cerebral blood flow (CBF), cerebral blood volume (CBV) and cerebral metabolic rate of oxygen (CMRO2). Thus, it is difficult to separate CMRO2 changes from CBF and CBV changes. To detect the BOLD signal changes induced only by CMRO2 responses without significant evoked CBF and CBV changes, BOLD and CBV functional mag...

ABSTRACT Time-resolved hemodynamic changes in the breast resulting from the application of external compression have recently been investigated as potential biomarkers of breast cancer [1]. Using high time-resolution near-infrared diffuse optical spectroscopy to monitor postcompression hemodynamics, our group was able to demonstrate the non-invasive estimation of breast tissue blood flow and ox...

In functional MRI, magnetic field inhomogeneities due to air-tissue susceptibility differences may lead to severe signal dropouts and geometric distortions in echo-planar images. Therefore, the inhomogeneities in the field are routinely minimized by shimming prior to imaging. However in fMRI, the Blood Oxygen Level Dependent (BOLD) effect is the measure of interest, so the BOLD sensitivity (BS)...

The relationship of the blood oxygen-level-dependent (BOLD) signal to its underlying neuronal activity is still poorly understood. Combined physiology and functional MRI experiments suggested that local field potential (LFP) is a better predictor of the BOLD signal than multiunit activity (MUA). To further explore this relationship, we simultaneously recorded BOLD and electrophysiological activ...

BACKGROUND AND PURPOSE Functional MR imaging with blood oxygen level-dependent (BOLD) contrast enhancement is believed to rely on changes in cerebral blood flow and deoxyhemoglobin level to estimate the location and degree of neural activation. We studied the relationship between neural activation and the observed BOLD response by using theophylline, an antagonist of the inhibitory neurotransmi...