Functional diffusion tensor imaging at 3 Tesla

Abstract

In a previous study we reported on a non-invasive functional diffusion tensor imaging (fDTI) method to measure neuronal signals directly from subtle changes in fractional anisotropy along white matter tracts. We hypothesized that these fractional anisotropy changes relate to morphological changes of glial cells induced by axonal activity. In the present study we set out to replicate the results of the previous study with an improved fDTI scan acquisition scheme. A group of twelve healthy human participants were scanned on a 3 Tesla MRI scanner. Activation was revealed in the contralateral thalamo-cortical tract and optic radiations during tactile and visual stimulation, respectively. Mean percent signal change in FA was 3.47% for the tactile task and 3.79% for the visual task, while for the MD the mean percent signal change was only -0.10 and -0.09%. The results support the notion of different response functions for tactile and visual stimuli. With this study we successfully replicated our previous findings using the same types of stimuli but on a different group of healthy participants and at different field-strength. The successful replication of our first fDTI results suggests that the non-invasive fDTI method is robust enough to study the functional neural networks in the human brain within a practically feasible time period.

Voxel-wise comparisons of cellular microstructure and diffusion-MRI in mouse hippocampus using 3D Bridging of Optically-clear histology with Neuroimaging Data (3D-BOND)

“…stroke, and 3D-BOND maybe useful in further exploring regional variation in normal vascular density, and the sensitivity of dMRI to local changes in the vasculature. In the case of the microvasculature, it will be necessary to also perform dMRI in vivo rather than just ex vivo , as patent, flowing vascular networks will have a different effect on diffusion signal at certain b-values 37 than that suggested by the microstructure alone, and neuronal activity has been implicated in inducing diffusion changes where hemodynamic changes may be a contributing factor 39 .…”

Task-relevant brain networks identified with simultaneous PET/MR imaging of metabolism and connectivity

“…Finally, mean values of L1 and RD were extracted across the entire tract for rest and task conditions. Averaging of diffusion metrics across an entire tract increases signal-to-noise ratio and is thus less susceptible to spurious findings (Mandl et al 2013 ). For visualization purposes but not for quantitative assessment, individual tracts were also registered to MNI-space and averaged across subjects.…”

Physical Exercise Keeps the Brain Connected: Biking Increases White Matter Integrity in Patients With Schizophrenia and Healthy Controls

“…A growing body of evidence suggests possibly direct contributions of activation of fiber bundles to changes in white matter. 84 Alternatively, the effect in white matter may be due to improvements in cardiorespiratory fitness, as suggested by positive associations between FA and cardiorespiratory fitness parameters over time. Moreover, these associations imply that changes are caused by practice of an overlearned aerobic activity rather than anaerobic newly learned exercise.…”