You Remember Your Childhood Friend, But Forget the Name Of Someone You Just Met

Why is that you remember the name of a childhood friend but forget the name of someone you met very recently?

A new study done on neural activity in mice showed how they learn about and remember a new place when put within a cage. Various symbols were put on the 5 feet long walls such as a bold plus sign or angled slash.  Sugar water was also kept in two places. While the mouse was exploring, the researchers measured the activity of specific neurons in the mouse hippocampus (the region in the brain where new memories are formed).
Initially, the mouse wandered here and there but once it came to sugar water and it became familiar with its location after multiple experiences. The researchers noted that rats became familiar with the symbols on the wall and remembered the locations with respect to each symbol. The activity was repeated on the same enclosure after twenty days. This time it was evident that its movements showed that strong memories had been formed by higher number of neurons. Using of groups of neurons enables the brain to have redundancy and still recall memories even if some of the original neurons fall silent or are damaged. 
Memory is so fundamental to human behavior and loss of it can impact the quality of life. However, fading of memory happens with ageing and some diseases such as Alzheimers disease or accidents that affect the neuro systems. 
The new study points to the possibility of designing treatments that could boost the recruitment of a higher number of neurons to encode a memory could help prevent memory loss. 
The researchers involved in the study were Carlos Lois, research professor of Biology, faculty member of the Tianquioa and Chrissy Chen Institute for Neuroscience at Caltech and Walter Gonzales,postdoctoral scholar. The paper titled 'Persistence of neuronal representations through time and damage in the hippocampus was published in the journal Science Aug 23. "For years, people have known that the more you practice an action, the better chance that you will remember it later," says Lois. "We now think that this is likely, because the more you practice an action, the higher the number of neurons that are encoding the action. The conventional theories about memory storage postulate that making a memory more stable requires the strengthening of the connections to an individual neuron. Our results suggest that increasing the number of neurons that encode the same memory enables the memory to persist for longer."

https://www.caltech.edu/about/news/how-memories-form-and-fade