Recently published research in Nature provides new insight into the process of remembering things. It takes collaboration from several brain regions to recall past experiences.
When you dine at a restaurant, you never forget that the experience isn’t just about the food. The ambiance, the music, the company, and even the décor all play a role in making the evening unforgettable. After a while, it might be enough to remember just one of these factors to recapture a memory of the entire evening.
The Importance of the Hippocampus in Memory Formation
These studies show that when it comes to memories, the more complicated, the better. The hippocampus, which is often thought to be the seat of memory, stores the general experience. Still, the prefrontal cortex, which is located in a different part of the brain, stores specific details. This separation ensures that, in the future, exposure to any one cue will be sufficient to activate the prefrontal cortex, which will then access the hippocampus to remember the entire memory. In other words, your memories will be retained in their entirety!
Using feelings and senses to recall memories
The study carried out by the researchers at Weill Cornell Medicine, and Rockefeller University provides new insight into how memories are recalled and sheds light on how the brain processes memories. This is important because memory storage is a process that is better understood than memory recall. The study found that memories are recalled in a specific order, which is determined by how the person feels when the memory is recalled.
For example, suppose you are feeling happy and excited about something that happened earlier in the day. In that case, your brain will likely recall the memory of that event in a happier and more exciting way. Conversely, if you are feeling sad or upset about something that happened earlier in the day, your brain will likely recall the memory of that event in a more sad or upset way.
This research has important implications for how we can better remember our past experiences. For example, if you want to remember a happy memory, make sure you are feeling happy and excited about it when you try and recall it. And if you want to remember a sad or upsetting memory, make sure you are feeling sad or upset about it when you try and recall it.
Memory as a distributed brain process has been hard to study, partly because our technology isn’t as good as it could be. Priya Rajasethupathy, a neuroscientist at Rockefeller University, and her colleagues came up with new ways to record and change neural activity from multiple parts of the brain simultaneously as mice moved through an endless corridor in virtual reality and encountered different sights, sounds, and smells. They were able to study memory as a distributed brain process because of the methods they came up with.
The Effects of Odor and Sound on Memory
The researchers taught the mice to associate different rooms containing their unique combination of sensory cues with either a positive or negative experience. Later on, when prompted by a particular odor or sound, the mice recalled the overall experience and knew whether to joyfully anticipate receiving sugar water or be on the lookout for an annoying puff of air.
The Different Pathways the Brain Uses to Store and Recall Information
The experiments showed that the individual sensory details were being sent to prefrontal neurons, even though the entorhinal-hippocampal pathway, a well-studied circuit that includes the hippocampus and its surroundings, was essential for the process of forming and storing experiences. In later experiments, when the mice were exposed to certain sensory features, a different circuit was turned on. This time, it was the prefrontal neurons that started talking to the hippocampus in order to get to the right global memory.
The dedicated pathway for memory recall
According to Nakul Yadav, the first author of the study and a graduate student at Weill Cornell Medicine, co-mentored by Rajasethupathy and Conor Liston, a neuroscientist at Weill Cornell Medicine, “This suggests that there is a dedicated pathway for memory recall, separate from memory formation.”
Prefrontal feature representations drive memory recall
These findings have significant implications for treating conditions like Alzheimer’s, where it’s believed that the deficits are more closely related to memory recall than memory storage. According to Rajasethupathy, the fact that the brain has distinct pathways for storing information and retrieving information suggests that targeting the prefrontal recall pathways may be a more promising therapeutic approach.