Scientists present method for mapping the brain’s environment

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Easily orient yourself when entering the kitchen in the morning. To brew coffee, approach a specific location. Maybe you go into your pantry, grab a quick breakfast, and then head to your car to head to work.

How these seemingly simple tasks are performed is of great interest to neuroscientists at Baylor College of Medicine, Stanford University, and collaborating institutions. Their study, published in the journal Science, significantly increases our understanding of how this happens by uncovering brain cell-level mechanisms that mediate how animals move around in their environments. Ta.

“The hippocampus, an area of ​​the brain that forms representations, is what allows animals and people to find their way in the environment, and is like a map of the environment that tells us where we are.” “is known,” said the co-lead author. Dr. Verna Dudok, assistant professor of neurology at Baylor University and McNair Scholar. Dudok is also co-corresponding author of this work.

Many brain cells, or neurons, within the hippocampus work together to create a map of a particular environment, such as your home’s kitchen. Scientists know that each of these neurons, called place cells, is activated only at specific locations in the environment. For example, the location of the coffee pot activates one place cell for him, and the pantry activates another place cell.

“Place cells help people know where they are,” Dudoku says. “When a person walks through a particular area of ​​the environment, cells in that particular location are activated, and when the person moves to another area, other cells are activated. In this study, we used mice to “Animals orient themselves in their environments. Specifically, the role of molecular messengers called endocannabinoids in the activity of place cells. I will prove the cost.”

When cells in the hippocampus become activated, endocannabinoids are released. Endocannabinoids are lipids, fat-like molecules that mediate communication between one neuron and the next.

“Until now, all the details about how endocannabinoids work have been explained in brain slices. This study shows how to record these signals at high resolution in living animals. This is the first time we have achieved this,” Dudok said.

Researchers used a microscope and molecular tools that convert endocannabinoid signals into fluorescence to image the brains of mice running on a treadmill.

“It was very rewarding for me to analyze these images and realize that there are endocannabinoid signals that can detect changes as the mouse moves through its environment,” Dudok said. “I’ve been studying this pathway for a long time, and I’ve always been able to see it in brain slices. It’s great to be able to actually see it happening in the brains of active animals. I was very excited.”

Remarkably, cells in a single activated location release endocannabinoids, and the signal disappears within seconds. “Previously, people suspected that this was a slow signal that spread to different cells, but this is a fast signal that is very specific to individual cells, which could potentially lead to an animal’s ability to encode information about its location. It seems to be contributing,” Dudoku said. .

Supporting the importance of endocannabinoid signaling in animal orientation, researchers say that disrupting this mechanism by eliminating endocannabinoid receptors in neurons disrupts the hippocampal circuitry that helps animals know their location. The researchers found that the map formed by the hippocampus becomes less accurate as a result.

This research also has implications for neurological disorders in humans. “Our group and others have previously shown that epileptic seizures trigger the release of endocannabinoids, and we want to understand whether this contributes to memory impairment in epilepsy patients.” Dudoku said. “This could lead to ways to prevent or reverse the reorganization of endocannabinoid signaling pathways in epilepsy and potentially improve cognitive comorbidities in this condition.”

Co-lead authors Linlin Z. Huang, Jordan S. Farrell, Shreya Malhotra, Jeslyn Homidan, Du-Kyung Kim, Celestine Wenardi, Charu Ramakrishnan, Yuron Lee, Carl Deisseroth, and Ivan Soltes also contributed to this work. The author is affiliated with one or more of his institutions: Baylor College of Medicine, Stanford University, Boston Children’s Hospital, Harvard Medical School, Peking University, and Howard Hughes Medical Institute.

This research was supported by the National Institute of Neurological Disorders and Stroke of the National Institutes of Health. Dudoku is a McNair Scholar supported by the Robert and Janice McNair Foundation’s McNair Institute for Medical Research.

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