Neuroscientists at the Technische Universität Dresden have discovered a new, non-invasive, imaging-based method to study the visual sensory thalamus, an important structure in the human brain and the point of origin of visual difficulties in diseases such as dyslexia and glaucoma. The new method could provide an in-depth understanding of visual sensory processing in health and disease in the near future.
The visual sensory thalamus is a key region that connects the eyes to the cerebral cortex. It contains two large compartments. Symptoms of many diseases are associated with alterations in this region. Until now, it has been very difficult to assess these two compartments in living humans, because they are tiny and located very deep inside the brain.
This difficulty in investigating the visual sensory thalamus in detail has significantly hampered understanding of the function of visual sensory processing in the past. Coincidentally, Christa Müller-Axt, a Ph.D. student in the lab of neuroscience professor Katharina von Kriegstein at the Technical University of Dresden, discovered structures that she thinks might resemble the two visual sensory compartments of the thalamus. in neuroimaging data.
The neuroimaging data was unique because it had unprecedented high spatial resolution obtained on a specialized magnetic resonance imaging (MRI) machine at MPI-CBS in Leipzig, where the group was researching developmental dyslexia. She followed this discovery in a series of novel experiments involving the analysis of high spatial resolution in vivo and post-mortem MRI data as well as post-mortem histology and was soon sure to have discovered the two main compartments of the visual sensory thalamus.
The results showed that the two main compartments of the visual sensory thalamus are characterized by different amounts of cerebral white matter (myelin). This information can be detected in new MRI data and can therefore be used to study the two compartments of the visual sensory thalamus in living humans.
The discovery that we can view the visual sensory compartments of the thalamus in living humans is fantastic, as it will be a great tool for understanding visual sensory processing in both health and disease in the near future. Post-mortem studies in developmental dyslexia have shown that there are alterations specifically in one of the two compartments of the visual sensory thalamus. However, there are very few of these post-mortem studies, so it is difficult to say whether all dyslexics are characterized by this type of visual sensory alterations of the thalamus. Moreover, post-mortem data cannot reveal anything about the functional impact of these alterations and their specific contribution to symptoms of developmental dyslexia. Therefore, we expect our new in vivo approach to be a major asset in facilitating research on the role of the visual sensory thalamus in developmental dyslexia.”
Christa Müller-Axt, first author
Technical University Dresden
Müller-Axt, C., et al. (2021) Mapping the human lateral geniculate nucleus and its cytoarchitectonic subdivisions using quantitative MRI. NeuroImage. doi.org/10.1016/j.neuroimage.2021.118559.