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Modern functional neuroimaging methods, such as positron-emission tomography (PET), optical imaging of intrinsic signals, and functional MRI (fMRI) utilize activity-dependent hemodynamic changes to obtain indirect maps of the evoked electrical activity in the brain. Whereas PET and flow-sensitive MRI map cerebral blood flow (CBF) changes, optical imaging(More)
Cross-modal binding in auditory-visual speech perception was investigated by using the McGurk effect, a phenomenon in which hearing is altered by incongruent visual mouth movements. We used functional magnetic resonance imaging (fMRI) and positron emission tomography (PET). In each experiment, the subjects were asked to identify spoken syllables ('ba',(More)
We investigated the relationship between evoked local cerebral blood flow (LCBF) and the field potential induced by somatosensory activation. The specific aim of the present study was to examine the correlation between variations of evoked LCBF and field potential when the stimulus duration was changed, and the dependency of the correlation on stimulus(More)
In quantitative functional neuroimaging with positron emission tomography (PET) and magnetic resonance imaging (MRI), cerebral blood volume (CBV) and its three components, arterial, capillary, and venous blood volumes are important factors. The arterial fraction for systemic circulation of the whole body has been reported to be 20-30%, but there is no(More)
In many studies on functional neuroimaging, change in local cerebral blood flow induced by sensory stimulation (evoked LCBF) is used as a marker for change in cortical neuronal activity, although a full description of the relationship between the evoked LCBF and neuronal activity has not been given. The purpose of this study was to estimate the close(More)
The discrepancy between the increases in cerebral blood flow (CBF) and CMRO2 during neural activation causes an increase in venous blood oxygenation and, therefore, a decrease in paramagnetic deoxyhemoglobin concentration in venous blood. This can be detected by functional magnetic resonance imaging (fMRI) as blood oxygenation level-dependent (BOLD)(More)
OBJECTIVE A fully automatic multimodality image registration algorithm is presented. The method is primarily designed for 3D registration of MR and PET images of the brain. However, it has also been successfully applied to CT-PET, MR-CT, and MR-SPECT registrations. MATERIALS AND METHODS The head contour is detected on the MR image using a gradient(More)
Measurement of cerebral blood flow (CBF), cerebral blood volume (CBV), cerebral oxygen extraction fraction (OEF) and cerebral metabolic rate of oxygen (CMRO(2)) by positron emission tomography (PET) with oxygen-15 labelled carbon dioxide (C(15)O(2)) or (15)O-labelled water (H(2)(15)O), (15)O-labelled carbon monoxide (C(15)O) and (15)O-labelled oxygen(More)
Hypercapnia induces cerebral vasodilation and increases cerebral blood flow (CBF), and hypocapnia induces cerebral vasoconstriction and decreases CBF. The relation between changes in CBF and cerebral blood volume (CBV) during hypercapnia and hypocapnia in humans, however, is not clear. Both CBF and CBV were measured at rest and during hypercapnia and(More)
A statistical method for detecting activated pixels in functional MRI (fMIRI) data is presented. In this method, the fMRI time series measured at each pixel is modeled as the sum of a response signal which arises due to the experimentally controlled activation-baseline pattern, a nuisance component representing effects of no interest, and Gaussian white(More)