How does the brain learn to link things together?

We constantly link different things together: new kids and their names, faces and voices, green eggs and ham. How does our brain achieve this? The purpose of this study was to understand how the brain creates these links. What happens in brain cells when we learn that two things (e.g., a new kid and her name) go together? In an experiment we asked human participants to learn to link different items together. As the participants learned these links, we found that nerve cells in their brains also linked these items together. These nerve cells were found in a region of the brain called the hippocampus. In this article, we will first explain how it is possible to listen to nerve cells in the human brain. Then we will show some examples of the responses of these nerve cells, and finally, how the cells can link different items together.