The blood oxygenation level-dependent (BOLD) response has been strongly associated with neuronal activity in the brain. However, some neuronal tuning properties are consistently different from the BOLD response. We studied the spatial extent of neural and hemodynamic responses in the primary visual cortex, where the BOLD responses spread and interact over much longer distances than the small re...

We compare fMRI-BOLD responses in anesthetized cats with local field potentials (LFPs), aggregate high-frequency responses (analog-Mua) and spiking activity recorded in primary and higher visual cortex of alert animals. The similarity of the activations in these electrophysiological signals to those in the BOLD is quantified by counting recording sites where different stimuli elicit the same re...

Introduction Studies comparing visual evoked potentials (VEPs) and BOLD signals have found a positive correlation between the VEP amplitude and the magnitude and extent of the BOLD signal [1, 2], but some VEP components are better related to the BOLD signal than others. The strongest spatial correlation have been found between the source location of the N1 peak* and the location of the BOLD sig...

Blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI) is widely used in neuroscience to study brain activity. However, BOLD fMRI does not measure neuronal activity directly but depends on cerebral blood flow (CBF), cerebral blood volume (CBV), and cerebral metabolic rate of oxygen (CMRO(2)) consumption. Using fMRI, CBV, CBF, neuronal recordings, and CMRO(2) modeling, ...

The purpose of the present study was to gain more insight into the blood oxygen level-dependent (BOLD)-contrast functional MRI (fMRI) in the brain and its connection to EEG, both in global and local scales of their temporal and spatial relations. BOLD signal changes were studied during hyperventilation (HV) induced EEG reactivity of intermittent rhythmic delta activity (IRDA). The BOLD signal i...

The nonlinear properties of spontaneous fluctuations in blood oxygen level-dependent (BOLD) signals remain unexplored. We test the hypothesis that complexity of BOLD activity is reduced with aging and is correlated with cognitive performance in the elderly. A total of 99 normal older and 56 younger male subjects were included. Cognitive function was assessed using Cognitive Abilities Screening ...

Functional magnetic resonance imaging (fMRI) using the blood oxygen level-dependent (BOLD) contrast was used to study sensory processing in the brain of isoflurane-anesthetized mice. The use of a cryogenic surface coil in a small animal 9.4T system provided the sensitivity required for detection and quantitative analysis of hemodynamic changes caused by neural activity in the mouse brain in res...