September 30, 2016
TORONTO, Canada – Neuroscience researchers at the Rotman Research Institute at Baycrest Health Sciences have identified the brain pathways that influence eye movements in relation to memories, rewriting the decades old textbook explanations of the brain’s connection to the eyes. The results of this study will lead to a new understanding of eye tracking tests that can detect signs of dementia.
Dr. Kelly Shen, lead investigator and research associate at the Rotman Research Institute, says her team’s findings demonstrate that there are no direct connections between the eyes and the parts of the brain that manage memories. However, a complex set of multistep brain pathways allow information to flow freely. She says her findings, published in the Journal of Cognitive Neuroscience, explain a missing link in memory and eye movement research that has been missing from diagrams in most neuroscience textbooks.
“Past studies have shown us how damage to the hippocampus, a part of the brain that plays an important role in short and long-term memory, can cause memory loss and change eye movement behaviour, but we had no knowledge of how that information flowed in the brain, says Dr. Shen. “As there are no direct connections from the hippocampus to the eye movement system in the brain, it was a complete mystery how information moves from one part of the brain to another.
Using data from past studies, Dr. Shen examined 75 regions in the brain to search for connectivity from the hippocampus to the oculomotor system, a part of the central nervous system that controls eye movements. The data revealed that while there are no direct connections between the eyes and the parts of the brain that manage memories, there are multiple routes involving other “intermediary brain areas that share information back and forth.
“At the beginning of this study we had no idea how our brains used memories to observe and gather information from the world around us, says Dr. Shen. “Now, we have a greater understanding of the memory system highways in the brain that drive our eyes’ movements.
Dr. Jennifer Ryan, co-author and senior scientist at the Rotman Research Institute and Canada Research Chair in Cognitive Neuroscience of Memory, says these findings will drive many future studies. “In addition to potentially helping detect signs of dementia through eye tracking tests, these results may lead to eye training exercises to boost memory.
As this study looked at the structure of connections in the brain and the oculomotor system, the data does not yet reveal the activity or function of the information being shared between the hippocampus and the systems that control the eyes. A series of new tests are planned to explore these areas in the coming months.
This study was made possible with support from the Natural Sciences and Engineering Research Council of Canada (NSERC) and the James S. McDonnell Foundation.
About Baycrest Health Sciences
Headquartered on a 22-acre campus and fully affiliated with the University of Toronto, Baycrest Health Sciences is unique in the world, combining a comprehensive system of care for aging adults and one of the world’s top research institutes in cognitive neuroscience (the Rotman Research Institute). Baycrest’s dedicated centres focus on mitigating the impact of age-related illness and impairment, and offer unmatched global knowledge exchange and commercialization capacity.
About Baycrest’s Rotman Research Institute
The Rotman Research Institute at Baycrest Health Sciences is a premier international centre for the study of human brain function. Through generous support from private donors and funding agencies, the institute is helping to illuminate the causes of cognitive decline in seniors, identify promising approaches to treatment, and lifestyle practices that will protect brain health longer in the lifespan.
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