Julien Valette from Commissariat à l’Energie Atomique - MIRCen, Fontenay-aux-Roses in France is visiting Aarhus and will give a CFIN & MIB guest talk on: "Diffusion-Weighted NMR Spectroscopy In Vivo to Probe Brain Cell Structure… and Beyond"

30.08.2019 | Henriette Blæsild Vuust

Julien Valette

Commissariat à l’Energie Atomique - MIRCen
Fontenay-aux-Roses
France

Diffusion-Weighted NMR Spectroscopy In Vivo to Probe Brain Cell Structure… and Beyond

Diffusion-weighted NMR spectroscopy (DW-MRS) offers the unique ability to non-invasively quantify the diffusion of endogenous brain metabolites in vivo. In contrast to water molecules, which are ubiquitous in biological tissues, most brain metabolites are confined into the intracellular space. Furthermore, some metabolites are even thought to exhibit preferential cellular compartmentation (i.e. in neurons or in glial cells). It is thus expected that DW-MRS may provide cell-specific information about the intracellular space.

In the first part of this presentation, we will see how basic understanding of brain intracellular metabolite diffusion as measured using DW-MRS in vivo has progressed over recent years, allowing relevant interpretation of DW-MRS in terms of cellular structure. It is now increasingly clear that DW-MRS primarily reports diffusion in long and thin cellular fiber, and that some quantitative information about these fibers can be extracted with diffusion modeling. This opens new possibilities for cell-specific microstructure quantification under normal and pathological conditions, as illustrated in a mouse model of astrocyte reactivity.

In the second part of this presentation, we will evoke the possibility to use DW-MRS to go beyond the sole determination of cell structure. Starting from the observation of massive variations of lactate diffusion (which, unlike other metabolites, is not purely intracellular) in the mouse model of reactive astrocytes, I will propose the idea that DW-MRS might be used to assess the distribution of brain lactate between neurons, astrocytes and the extracellular space, which is a highly relevant neuroscience question related to the astrocyte-to-neuron lactate shuttle. In relation with this idea, I will finally present very recent data collected after injecting sucrose directly in the extracellular space, in an attempt to characterize diffusion properties in the extracellular space over a broad range of diffusion modalities.

ALL ARE WELCOME

Read more at: 

http://www.cea.fr/english/Pages/cea/international-policy/european-community/erc/valette-portrait-brain.aspx

https://www.researchgate.net/profile/Julien_Valette