Various MRI approaches have been used to study brain anatomy and function, including novel ways to investigate the brains functional subdivision based on the spatio-temporal structure of spontaneous activity, and ways to reveal microstructural information by studying magnetic susceptibility contrast. Notably, a method to analyze spontaneous brain activity was developed and applied to a publicly available database of fMRI studies. It was demonstrated that, by clustering activity patterns at individual fMRI time frames, brain areas with a functional relationship can be revealed that escape detection by conventional methods. To identify the neurophysiological correlate of these fMRI signals, the analysis method is now being applied to electrical recordings from primate brain. Together with a several other approaches to study spontaneous brain activity, this work has let to a number of publications. AMRI has continued to study brain anatomy by exploiting magnetic susceptibility contrast. A major development over the last year has been the extraction of cellular compartment-specific information in white matter. Magnetic field modeling studies performed by AMRI and two other groups have shown that an anisotropic susceptibility of the myelin sheath will lead to distinct field effects in the various water compartments in white matter, specifically axonal, interstitial, and myelin water. These field effects lead to characteristic signal decay effects that can be observed by multi-echo MRI techniques. Using dedicated experiments on marmoset brain, we have investigated whether analysis of the signal decay curve allows recovering this compartment specific information. One of the goals of this has been to quantify axonal myelination. Promising results in marmosets have led to initial application to healthy human subjects and MS patients, a collaborative project that is ongoing. In parallel, acquisition and analysis techniques are being refined to optimize myelin quantification. One ongoing effort is the use of magnetization transfer contrast to improve the sensitivity, and develop improve understanding of the complex MRI signal generation mechanism in white matter.
| Liu, Xiao; Zhang, Nanyin; Chang, Catie et al. (2018) Co-activation patterns in resting-state fMRI signals. Neuroimage 180:485-494 |
| de Zwart, Jacco A; van Gelderen, Peter; Schindler, Matthew K et al. (2018) Impulse response timing differences in BOLD and CBV weighted fMRI. Neuroimage 181:292-300 |
| Turchi, Janita; Chang, Catie; Ye, Frank Q et al. (2018) The Basal Forebrain Regulates Global Resting-State fMRI Fluctuations. Neuron 97:940-952.e4 |
| Duyn, Jeff H (2018) Studying brain microstructure with magnetic susceptibility contrast at high-field. Neuroimage 168:152-161 |
| Liu, Xiao; de Zwart, Jacco A; Schölvinck, Marieke L et al. (2018) Subcortical evidence for a contribution of arousal to fMRI studies of brain activity. Nat Commun 9:395 |
| Özbay, Pinar S; Chang, Catie; Picchioni, Dante et al. (2018) Contribution of systemic vascular effects to fMRI activity in white matter. Neuroimage 176:541-549 |
| Jiang, Xu; van Gelderen, Peter; Duyn, Jeff H (2017) Spectral characteristics of semisolid protons in human brain white matter at 7 T. Magn Reson Med 78:1950-1958 |
| Shmueli, K; Dodd, S J; van Gelderen, P et al. (2017) Investigating lipids as a source of chemical exchange-induced MRI frequency shifts. NMR Biomed 30: |
| Mandelkow, H; de Zwart, J A; Duyn, J H (2017) Effects of spatial fMRI resolution on the classification of naturalistic movies. Neuroimage 162:45-55 |
| Duyn, Jeff H; Schenck, John (2017) Contributions to magnetic susceptibility of brain tissue. NMR Biomed 30: |
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