Diffusion Tensor Imaging (DTI) is a central tool in brain research and in the clinical neurological diagnosis. Despite its popularity in research and in clinical applications, the biophysical mechanisms underlying DTI are not fully understood. For example, with respect to essential parameters such as the amplitude of change of the apparent displacement post insults, the orientation of maximal change and its timing, theoretical models of displacement fail to describe the kinetics of water displacement following insults. Moreover, it was suggested that neuronal activity can directly modify the diffusion weighted MR signal to provide functional images with high temporal and spatial resolution. Our working hypothesis is that water displacement that occurs due to active cellular mechanisms, contributes significantly to the signal measured in DTI. We are interested in quantifying the contribution of various cellular events to the signal measured in DTI, where a pivotal mechanism that will explored is the suggested water displacement that is linked with neuronal activation. To address the limits of detectability of neuronal excitation via MR, we suggest employing a three-source, multi-modal system: MRI, electrical potential mapping and fluorescence microscopy of neuronal organotypic cell cultures. The use of organotypic cultures bypasses major sources of physiological artifacts such as blood flow and pulsation. MRI is performed with a low-field open MRI system. Electrical recordings will be performed simultaneously with a multi-electrode array system that will provide 2-D ‘imaging’ of neuronal electrical activity and optical microscopy will allow imaging of Calcium release. This multi-modal imaging system will allow testing previously proposed mechanisms of neural detection by MRI and will provide a test-bed to enable us to develop new ones.
Field of science
- /natural sciences/physical sciences/optics/microscopy
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