You might wonder what mice perched on a circular stage inside a 360-degree virtual-reality dome might have to do with dementia, but studying the way the brain orients and adjusts based on visual surroundings offers insights into what happens when neurodegeneration causes people to feel lost in familiar settings.
Scientists from McGill University have used the latest in neuronal mapping technology to study the firings of head direction (HD) cells in mice. They identified a phenomenon they’ve named “network gain,” in which the brain’s internal compass resets after the mice had been disoriented.
“It’s as if the brain has a mechanism to implement a reset button allowing for rapid reorientation of its internal compass in confusing situations,” said study co-lead author Zaki Ajabi, a former McGill University student, now at Harvard University.
HD cells, which were only discovered in rats in 1983, are thought to be common to all mammals. These neurons are located in several brain regions and their firing rate changes based on head movement. Only recent advances in neuronal recording technology has made it possible for researchers to properly study these cells’ behaviors. With this, the researchers could see how HD cells supported the brain’s ability to reorient after a change in surroundings.
“Neuroscience research has witnessed a technology revolution in the last decade allowing us to ask and answer questions that could only be dreamed of just years ago,” says study co-author Mark Brandon, an associate professor of psychiatry at McGill University and researcher at the Douglas Research Centre.
The new insights into a complex and under-researched part of the brain shed light on how the brain recalibrates in changing environments, and how this process goes awry with degenerative neural diseases such as dementia, and specifically, Alzheimer’s disease.
“One of the first self-reported cognitive symptoms of Alzheimer’s is that people become disoriented and lost, even in familiar settings,” says Brandon, who hopes that a better understanding of how our internal compass works will make any detected glitches in the system lead to earlier detection of neurodegeneration and even treatments for this aspect of it.
The researchers add that even though the animals were exposed to unnatural visual experience, it’s relevant to human life experience and, according to Ajabi, “may eventually explain how virtual-reality systems can easily take control over our sense of orientation.”
“This work is a beautiful example of how experimental and computational approaches together can advance our understanding of brain activity that drives behavior,” said co-author Xue-Xin Wei, a computational neuroscientist and and assistant professor at The University of Texas at Austin.