Neuroscientists at University College London (UCL) used laser beams to “turn on” neurons in mice, provide new insight into the latent activity of memory and point out how memory strengthens the brain’s internal GPS system.
The research is published in the journal UMBRELLA, explaining how researchers exploited an ‘all-optical’ approach using double lasers to simultaneously read and record the activity of a ‘site cell’ (a type of nerve cell). in the mouse, as they navigate in virtual reality.
Notably, by stimulating the place cells, the scientists were able to re-activate (or regain) the location where the rats received the reward, thereby “teleporting”;. rats, making them act as if they were in a reward. place.
This new research builds on the groundbreaking work of Professor John O’Keefe (UCL Cell & Developmental Biology), who won the 2014 Nobel Prize for discovering place cells. These cells are found in a brain region called the hippocampus, and are only active when the animal enters a specific location in the environment.
The location plots are supposed to represent an environmental awareness map – like an internal GPS – and retain location memories. The new UCL study is the first to directly show that local cell activity underlies the brain’s ability to navigate.
The results provide deeper insights into how memory is stored and UCL scientists believe that the final findings could help us develop new therapies for conditions like dementia. and Alzheimer Diseases affecting memory.
The first author, Dr. Nick Robinson (UCL Wolfson Biomedical Research Institute) said: “These results provide direct causal evidence that mice use information represented by cell activity to guide their behavior. In other words, the positional cells actually tell the mouse where its position is and the mouse actually ‘listens’ to the cells for their location when they make a decision. This provides new insights into how memories are stored in the brain, as well as new tools to manipulate these memories to influence behavior.
He added: “Memory disorders – such as dementia and Alzheimer’s disease – pose a huge cost to society. This work could eventually lead to a better understanding of these diseases, as well as new targets for therapeutic intervention.
Lead author Professor Michael Hausser (UCL Wolfson Biomedical Research Institute) said: “This study is a game-changing tool because it shows that we can use optical reading and writing. of work in specific nerve cells to control memory, allowing us to better understand – and potentially improve – how neural circuits work to help us make decisions. “
Explanatory test study
Researchers at the UCL Wolfson Biomedical Research Institute have leveraged a powerful approach that combines two revolutionary technologies in using light to read and write electrical activity in the brain.
First, they engineered neurons to express genetically coded calcium sensors, allowing the cells to light up as they function. Second, they express light-sensitive ‘genetically’ proteins within the same nerve cells, allowing them to activate specific cells with laser beams, which are targeted using use three-dimensional digital (the same technology used in laser light shows).
By combining these two techniques, the team was able to record and control activity in the same nerve cells in the brain of a navigational mouse in virtual reality.
UCL scientists have used this approach to target activation of location cells in the hippocampus in mice navigating to a specific location in the virtual world to collect a reward. sugar water. First, they recorded the activity of a large number of hippocampus cells, identified the specific active cells at the rewarded site and could thus form the basis for site memory. there. They then used the three-dimensional targeted laser beam to activate these positional cells at another location in the virtual world.
Notably, stimulating the position cell is sufficient to access the rewarded location’s memory, leading the mouse to search for a reward in a new location. In other words, the stimulation of the nerve cells with the animal’s “teleport” light causes them to act as if they were in the place of the reward. This is the first demonstration of how the activation of place cells allows us to retrieve our memories of our environment and help us navigate.
See: “Targeted activation of a place cell in the hippocampus promotes memory-guided spatial behavior” by Nick TM Robinson, Lucie AL Descamps, Lloyd E. Russell, Moritz O. Buchholz, Brendan A. Bicknell, Georgy K. Antonov, Joanna YN Lau, Rebecca Nutbrown, Christoph Schmidt-Hieber and Michael Häusser, November 6, 2020, UMBRELLA.
DOI: 10.1016 / j.cell.2020.09.061
Funding for this study was provided by Wellcome, Gatsby Charitable Foundation, European Commission, European Molecular Biology, Medical Research Council and European Research Council.