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A recent breakthrough study by researchers at Simon Fraser University (SFU) has uncovered a previously overlooked type of indirect brain damage that plays a crucial role in the long-term disability often experienced by stroke survivors. The research, published in the Proceedings of the National Academy of Sciences, focuses on how the thalamus—a central brain hub responsible for regulating critical functions like language, memory, attention, and movement—suffers significant disruption months or even years after a stroke, despite not being directly affected by the initial event.
Lead author Phillip Johnston, a graduate student at SFU’s Institute for Neuroscience and Neurotechnology, explains that while the brain tissue damaged by the stroke lesion is often well understood, the indirect damage to the thalamus has largely been overlooked. “Our findings suggest that this indirect damage to the thalamus plays an under-explored role in the abnormal brain activity and the long-term disabilities that commonly follow a stroke,” Johnston said.
The thalamus, which serves as a central communication hub within the brain, is highly connected to other regions via long axonal pathways. The study discovered that when a stroke injures axons in other areas of the brain, the resulting damage can travel to and disrupt neurons in the thalamus, impairing its function. This disruption can then affect the broader brain functions the thalamus typically regulates, leading to lasting cognitive and motor impairments in stroke survivors.
Unlike the tissue directly damaged by a stroke, the thalamus does not undergo immediate cell death but instead suffers a gradual disruption in its function. “This suggests that the thalamus might still have some potential for recovery, offering hope for new therapies aimed at restoring its function or preventing the disruption from occurring in the first place,” said Johnston.
To reach these conclusions, the researchers recorded the brain activity of 18 chronic stroke patients and analyzed the data using computer models to understand how abnormal thalamic function might contribute to ongoing impairments. The results showed a clear correlation between the level of indirect damage to the thalamus and the degree of impairment experienced by the patients.
This discovery opens up new avenues for treatment strategies that could target the thalamus and its communication networks. Researchers are hopeful that therapies such as drug treatments or brain stimulation could help restore normal thalamic function or protect it from damage in the first place, potentially alleviating some of the long-term effects of stroke.
Randy McIntosh, a co-author of the study and researcher at SFU’s Institute for Neuroscience and Neurotechnology, emphasized that the findings raise important questions about the specific mechanisms behind stroke-related disability. “The thalamus could experience several different types of damage after a stroke, and it remains unclear whether one particular type or a combination of factors causes the abnormal brain activity observed in these patients,” McIntosh explained. “A key next step will be to investigate how indirect thalamic damage evolves over time, especially during the critical hours and days following a stroke.”
This pioneering research was conducted in collaboration with SFU’s Institute for Neuroscience and Neurotechnology and the Rotman Research Institute at the University of Toronto, offering a new perspective on the long-term impacts of stroke and potential treatment approaches.
For more information, the study can be accessed in the Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.2409345121.
