Summary: A study of people learning to read braille reveals how white matter reorganizes itself across different brain regions and timeframes to meet the brain’s needs.
Source: SfN
Learning changes the brain, but when learning Braille different brain regions strengthen their connections at varied rates and time frames.
A new study published in Journal of Neuroscience highlights the dynamic nature of learning-induced brain plasticity.
Learning new skills alters the brain’s white matter, the nerve fibers connecting brain regions. When people learn to read tactile Braille, their somatosensory and visual cortices reorganize to accommodate the new demands.
Prior studies only examined white matter before and after training, so the exact time course of the changes was not known.
Molendowska and Matuszewski et al. used diffusion MRI to measure changes in the white matter strength of sighted adults as they learned Braille over the course of eight months. They took measurements at five time points: before the training, three times during, and once after.
White matter in somatosensory areas strengthened steadily over the course of the training. But white matter in the visual cortex did not reorganize until halfway through the training, the point where the Braille words start to take on semantic meaning. White matter in both regions went back to the pre-training level two and a half months after the training ended.
These results demonstrate white matter reorganizes itself across regions and different timeframes to meet the brain’s needs.
About this neuroplasticity research news
Source: SfN
Contact: Calli McMurray – SfN
Image: The image is credited to Molendowska and Matuszewski et al., JNeurosci 2021
Original Research: Closed access.
“Temporal Dynamics of Brain White Matter Plasticity in Sighted Subjects During Tactile Braille Learning – a Longitudinal Diffusion Tensor Imaging Study” by Malwina Molendowska, Jacek Matuszewski, Bartosz Kossowski, Łukasz Bola, Anna Banaszkiewicz, Małgorzata Paplińska, Katarzyna Jednoróg, Bogdan Draganski and Artur Marchewka. Journal of Neuroscience
Abstract
Temporal Dynamics of Brain White Matter Plasticity in Sighted Subjects During Tactile Braille Learning – a Longitudinal Diffusion Tensor Imaging Study
The white matter (WM) architecture of the human brain changes in response to training, though fine-grained temporal characteristics of training-induced white matter plasticity remain unexplored.
We investigated white matter microstructural changes using diffusion tensor imaging at 5 different time points in 26 sighted female adults during 8-months training of tactile Braille reading. Our results show that training-induced white matter plasticity occurs both within and beyond the trained sensory modality, as reflected by fractional anisotropy (FA) increases in somatosensory and visual cortex, respectively.
The observed changes followed distinct time courses, with gradual linear FA increase along the training in the somatosensory cortex and sudden visual cortex cross-modal plasticity occuring after Braille input became linguistically meaningful. WM changes observed in these areas returned to baseline after cessation of learning in line with the supply-demand model of plasticity.
These results also indicate that the temporal dynamics of microstructural plasticity in different cortical regions might be modulated by the nature of computational demands. We provide additional evidence that observed FA training-induced changes are behaviorally relevant to tactile reading.
Taken together, these results demonstrate that WM plasticity is a highly dynamic process modulated by the introduction of novel experiences.
Significance statement
Throughout the lifetime the human brain is shaped by various experiences. Training-induced reorganization in white matter (WM) microstructure has been reported, but we know little about its temporal dynamics. To fill this gap we scanned sighted subjects 5 times during tactile Braille reading training.
We observed different dynamics of WM plasticity in the somatosensory and visual cortices implicated in Braille reading. The former showed continuous increase in WM tissue anisotropy along with tactile training, while microstructural changes in the latter were observed only after the participants learned to read Braille words.
Our results confirm the supply-demand model of brain plasticity and provide evidence that WM reorganization depends upon distinct computational demands and functional roles of regions involved in the trained skill.
