In an experiment to identify areas of the brain associated with memory control, we used the habit of mice that like sugar water. Picture of a pet rat drinking water. Courtesy of Wikimedia
Scientists have found that parts of the brain that were not previously known to be involved in managing memories play an important role in long-term memory storage. As a result of observing the brains of mice playing virtual reality (VR) games, it is evaluated that a new secret of the brain related to memory has been identified.
A joint research team of researchers Andrew Toder and Josue Regalado from Rockefeller University in the United States confirmed that the anterior ‘thalamus’ of the brain plays a major role in memory storage, and research results were published in the international journal ‘Cell’ on the 30th ( local time). . The thalamus is a region at the top of the center of the brain that receives sensory information and transmits it to all regions that process the information.
How quickly forgotten memories and permanent memories are selected and stored in the brain has been a long-standing interest in academia. The research team explained, “We discovered a new circuit in the anterior thalamus that is responsible for identifying and storing important long-term memories.”
The research team prepared a maze in the VR game space to observe how the mouse brain selects important memories. There are a total of three goal points in the maze, and the reward given to the rat is configured differently depending on the location reached. In the first room, a water container was placed with unlimited sugar water, which the rats like. The second room has a water trough with only a small amount of sugar water provided. In the last room, instead of sugar water, I put an empty water container with wind.
The rats who became the test subjects learned the way to each goal point for about three weeks. On the maze path to each room, there were characteristic obstacles that, when touched in the game, provided sound, smell, and visual stimuli in real life, helping the mice to remember the characteristics of each path.
Whether the rat moved based on memory depended on the time it took to reach the destination and the time it took to receive the reward. A mouse that remembered and moved to a room with a better reward took less time to reach the goal. Also, when they got to the bucket of unlimited sugar water, they licked the spout of the bucket for a longer period of time.
The research team confirmed the changes that occur in the brain when the memory behavior of these mice is observed. Using brain imaging tools, we observed activation patterns of the anterior cingulate cortex (ACC), hippocampus, and anterior thalamus. The anterior cingulate cortex surrounds the bundle of nerves that connect the left and right hemispheres. The hippocampus is located under the cortex of the brain and is involved in learning and memory. Most of these areas were active while the rats were exploring the maze. Among them, the anterior thalamic region was significantly activated.
The research team ran the experiment again while stopping the activity of each part to accurately investigate the actual effect of each part of the brain on memory storage. In the case of the anterior cingulate cortex and the hippocampus, there was no specific change in the memory behavior of the rats when the action was stopped or when the neurons in these areas were stimulated and activated. It did not significantly affect long-term memory capacity. On the other hand, stimulating the anterior thalamus directly improved the rats’ memory abilities. Rats stimulated in the anterior thalamus remembered not only the route to the destination with the best reward, but also routes to other rooms with less reward.
The research team explained that when a beneficial experience is experienced, the anterior thalamus promotes the release of adrenaline and dopamine, neurotransmitters that give a feeling of happiness. Through this, it selects important memories that need to be stored for a long time. The research team added, “However, follow-up research is needed on how long-term stored memories are stably managed.”