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An MRI time course of 512 echo-planar images (EPI) in resting human brain obtained every 250 ms reveals fluctuations in signal intensity in each pixel that have a physiologic origin. Regions of the sensorimotor cortex that were activated secondary to hand movement were identified using functional MRI methodology (FMRI). Time courses of low frequency (< 0.1(More)
We have recently demonstrated using functional magnetic resonance imaging the presence of synchronous low-frequency fluctuations of signal intensities from the resting human brain that have a high degree of temporal correlation (p < 0.0001) both within and across the sensorimotor cortex. A statistically significant overlap between the resting-state(More)
Data obtained from functional magnetic resonance imaging are often limited by a low signal-to-noise ratio. The time-course data obtained from activated regions contain both system noise and physiological noise, primarily linked to the heart and respiratory rates, that are superimposed on task induced signals. Time averaging of a practical number of data(More)
The premises of this work are: 1) the limit of spatial resolution in fMRI is determined by anatomy of the microcirculation; 2) because of cortical gray matter tortuosity, fMRI experiments should (in principle) be carried out using cubic voxels; and 3) the noise in fMRI experiments is dominated by low-frequency BOLD fluctuations that are a consequence of(More)
PURPOSE The objective of this study was to separate multiple signal components present in functional MRI (fMRI) data sets. Blind source separation techniques were applied to the analysis of fMRI data to determine multiple physiologically relevant independent signal sources. METHOD Computer simulations were performed to test the reliability and robustness(More)
Using magnetic resonance (MR) echo-planar imaging (EPI), we recently demonstrated the presence of low-frequency fluctuations (< 0.1 Hz) in MR signal intensity from the resting human brain that have a high degree of temporal correlation (p < 10(-3)) within and across associated regions of the sensorimotor cortex. These fluctuations in MR signal intensity are(More)
PURPOSE Our goal was to determine the distribution of auditory and language cortex activation in response to acoustic echo planar scanner noise with functional MRI (fMRI). METHOD Acoustic scanner noise and spoken text, reproduced on high output cassette tape, were separately delivered at equivalent intensities to six normal hearing adult volunteers(More)
PURPOSE Our goal was to determine the effects of acoustic echoplanar scanner noise on pure tone hearing thresholds in normal volunteers and to determine the influence of echoplanar sequence repetition time on threshold effects. METHOD With use of a calibrated audiometer, pure tones ranging from 125 to 8,000 Hz were delivered monaurally to 10(More)
Data acquired using functional magnetic resonance imaging are often contaminated by head motion. As a result, optimal information regarding task-induced (or resting-state) signal changes cannot be extracted. Intensity-based registration methods, including intensity correlation or minimum intensity variance techniques, are widely used to register two or more(More)
OBJECTIVE The goal was to assess auditory cortex activation evoked by pure-tone stimulus with functional MRI. METHODS Five healthy children, aged 7 to 10 years, were studied. Hearing evaluation was performed by pure-tone audiometry in a sound-treated room and in the MRI scanner with the scanner noise in the background. Subjects were asked to listen to(More)