Remapping a Damaged Mind

New insight on the hippocampus, which creates memories, could help patients dealing with neurological diseases.

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The hippocampus is part of the brain that is most known for its role in forming and retaining personal memories. But beyond allowing people to remember what they did yesterday, the hippocampus also helps people navigate their environments by helping them form a map-like representation of their surroundings.

Neuroscientist Shayna Rosenbaum, professor of psychology at York University and researcher at Vision: Science to Applications (VISTA), wants to know how to help patients with hippocampal damage recover as much memory-forming and navigation function as possible. It starts with understanding the complex relationships between functions of the hippocampus to help predict what happens when it becomes damaged.

Scientists believed for years that the hippocampus was needed to both form and retain new spatial memories, especially to create mental map-like representations of the world. However, Rosenbaum unexpectedly found that people with hippocampal damage could still navigate efficiently.

“What we were finding was that patients with hippocampal damage had little difficulty navigating in neighbourhoods in their day-to-day life,” says Rosenbaum. “They were able to get from their home to their school to a close-by mall.

“What we also found, though, is that although these individuals were able to navigate efficiently in their environments and retain those types of memories, what they were unable to do is describe those environments in any great detail.”

This was a vital clue that there may be other parts of the brain that were stepping up to help those patients navigate and live more independently. Indeed, Rosenbaum did locate parts of the brain outside the hippocampus that are needed in navigation, and these may be important in helping patients with hippocampal damage compensate. While precise details may be lost, general direction might be preserved.

“Our more recent work is looking at the level of precision that’s needed for the hippocampus to be involved, and this allows us to predict the types of deficits that we might see in a patient with Alzheimer’s disease who has significant atrophy at the hippocampus,” adds Rosenbaum.

“I really want to understand why it is that memory is so vulnerable to neurological disease, how it breaks down, and how we can help these individuals function in everyday life in a better way.”

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Shayna Rosenbaum is a professor and York Research Chair in the Department of Psychology and Vision: Science to Applications (VISTA) Program at York University, and is an Associate Scientist at the Rotman Research Institute at Baycrest. She is registered as a Clinical Neuropsychologist with the College of Psychologists of Ontario.

Rosenbaum received her PhD in psychology from the University of Toronto in 2004 and completed a postdoctoral fellowship at Rotman. She has published extensively on the topics of memory and spatial navigation, and has received awards for her neuroimaging and patient research, most recently the Early Career Award from the International Neuropsychological Society. Her research is funded by the Canadian Institutes of Health Research and the Natural Sciences and Engineering Research Council of Canada. She is an elected member of the Royal Society of Canada College of New Scholars, Artists, and Scientists and is a member of the Board of Trustees of the Ontario Science Centre.

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