Neuroimaging the Gut-Brain Axis: Influence of the Gut Microbiome on Brain Microstructure
John-Paul J. Yu1
1University of Wisconsin-Madison, Madison, WI, United States

Synopsis

With well-established associations between gut microbiome populations, brain structure and function, and neurological disease and neuropsychiatric illness, the concomitant changes in neural tissue microstructure occurring parallel to these changes in the composition of the gut microbiome remain poorly characterized. We present new evidence for the neural microstructural correlates underpinning these mechanistic changes, the association between specific gut microbiome populations and brain microstructure, and the role of the human gut microbiome in the microstructural complexity of the developing brain.

Altered gut microbiome populations are associated with a broad range of neurodevelopmental disorders including autism spectrum disorder and mood disorders. In animal models, modulation of gut microbiome populations via dietary manipulation influences brain function and behavior and has been shown to ameliorate behavioral symptoms. With striking differences in microbiome-driven behavior, we explored whether these behavioral changes are also accompanied by corresponding changes in neural tissue microstructure. Utilizing diffusion tensor imaging, we identified global changes in white matter structural integrity occurring in a diet-dependent manner. Analysis of 16S ribosomal RNA sequencing of gut bacteria also showed changes in bacterial populations as a function of diet. Changes in brain structure were found to be associated with diet-dependent changes in gut microbiome populations using a machine learning classifier for quantitative assessment of the strength of microbiome-brain region associations. Additional work exploring the contribution of the human gut microbiome in germ free and gnotobiotic mice demonstrate the critical contribution of the human gut microbiome in neurodevelopment and its role in fostering complex neural microstructure. These associations allow us to further test our understanding of the gut-brain-microbiota axis by revealing possible links between altered and dysbiotic gut microbiome populations and changes in brain structure, highlighting the potential impact of diet and metagenomic effects in neuroimaging.

Acknowledgements

No acknowledgement found.

References

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Proc. Intl. Soc. Mag. Reson. Med. 28 (2020)