What if one of the keys to understanding a person’s behavior were hidden in myelin? Wrapped around the brain’s nerve fibers, this thin lipid sheath acts as an electrical insulator that enables rapid and precise conduction of nerve impulses between different brain regions. Christine Tardif, a researcher at McGill University, is interested in the plasticity of myelin and its impact on the dynamics of brain networks. Her hypothesis is that simple variations in the myelination of certain white matter tracts could modulate how information flows through the brain and thus influence its functioning, as seen in several neurological and psychiatric disorders, including autism.
To explore this line of inquiry, her research laboratory [https://www.tardiflab.com/] has developed state-of-the-art quantitative magnetic resonance imaging techniques. Using high-field MRI scanners (3 and 7 teslas), including one—unique in Quebec—located at the McConnell Brain Imaging Centre at the Montreal Neurological Institute (the “Neuro”), Dr. Tardif and her team have obtained detailed, quantitative maps of myelin in vivo and in a non-invasive manner. These technological advances make it possible to navigate the extreme complexity of brain tissue and precisely distinguish the myelination of intersecting nerve fibers, establishing links between their myelination and their functional connectivity. Initial results show that myelin plays a key role in the synchronization of brain networks by modulating the speed at which signals propagate. The team also observed atypical myelination profiles in individuals carrying a genetic mutation associated with an increased risk of autism spectrum disorder.
Although still in the basic research stage, this work lays the groundwork for a better understanding of the brain differences observed in certain populations. The next steps will aim to validate the established models in larger clinical cohorts and to better understand how variations in myelin contribute to differences in connectivity and, ultimately, behavior. Ultimately, this knowledge could guide the development of new therapeutic approaches in areas where options are currently limited.
References
1. Lu, W. D., Nelson, M. C., Leppert, I. R., Campbell, J. S. W., Schiavi, S., Pike, G. B., Rowley, C. D., Daducci, A., & Tardif, C. L. (2025). Mapping the aggregate g-ratio of white matter tracts using multi-modal MRI. Imaging Neuroscience 3: IMAG.a.49. doi: https://doi.org/10.1162/IMAG.a.49
2. Nelson, M. C., Lu, W. D., Leppert, I. R., Hansen, H. A., Rowley, C. D., Misic, B., and Tardif, C. L. (in press). The role of white matter myelin in structural-functional network coupling. Communications Biology. doi: 10.1038/s42003-026-09813-6. PMID: 41896361
3. Lu, W. D., Martin, C. O., Jizi, K., Nelson, M. C., Jacquemont, S., and Tardif, C. L. (2025). Alterations in white matter tract myelination in carriers of copy number variations at the 16p11.2 locus. Paper presented at the annual meeting of the International Society for Magnetic Resonance in Medicine (ISMRM), Honolulu.