BOLD signal compartmentalization based on the apparent diffusion coefficient.

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2002-09

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Abstract

Functional MRI (fMRI) can detect blood oxygenation level dependent (BOLD) hemodynamic responses secondary to neuronal activity. The most commonly used method for detecting fMRI signals is the gradient-echo echo-planar imaging (EPI) technique because of its sensitivity and speed. However, it is generally believed that a significant portion of these signals arises from large veins, with additional contribution from the capillaries and parenchyma. Early experiments using diffusion-weighted gradient-echo EPI have suggested that intra-voxel incoherent motion (IVIM) weighting inherent in the sequence can selectively attenuate contributions from different vessels based on the differences in the mobility of the blood within them. In the present study, we used similar approach to characterize the apparent diffusion coefficient (ADC) distribution within the activated areas of BOLD contrast. It is shown that the voxel values of the ADCs obtained from this technique can infer various vascular contributions to the BOLD signal.

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Song

Allen W Song

Professor in Radiology

The research in our lab is concerned with advancing structural and functional MRI methodologies (e.g. fast and high-resolution imaging techniques) for human brain imaging. We also aim to improve our understanding of functional brain signals, including spatiotemporal characterizations of the blood oxygenation level dependent contrast and alternative contrast mechanisms that are more directly linked to the neuronal activities. Additional effort is invested in applying and validating the developed methods to study human functional neuroanatomy.

Woldorff

Marty G. Woldorff

Professor in Psychiatry and Behavioral Sciences

Dr. Woldorff's main research interest is in the cognitive neuroscience of attention. At each and every moment of our lives, we are bombarded by a welter of sensory information coming at us from a myriad of directions and through our various sensory modalities -- much more than we can fully process. We must continuously select and extract the most important information from this welter of sensory inputs. How the human brain accomplishes this is one of the core challenges of modern cognitive neuroscience. Dr. Woldorff uses a combination of electrophysiological (ERP, MEG) and functional neuroimaging (fMRI) methods to study the time course, functional neuroanatomy, and mechanisms of attentional processes. This multimethodological approach is directed along several main lines of research: (1) The influence of attention on sensory and perceptual processing; (2) Cognitive and attentional control mechanisms; (3) The role of attention in multisensory environments; (4) The interactive relationship between attention and reward; and (5) The role of attention in perceptual awareness.


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