Cells that light up together link up

A bowl of rice this morning

Key ideaA memory = links between nerve cells that lit up together

First, let’s learn to read the board you will see all the way through. Each dot is one nerve cell in the brain, and yellow dots are cells that are on right now. When you ate breakfast this morning, cells lit up together in the shape of a rice bowl. Then the blue lines between the dots that lit up together grow stronger. Those stronger lines are the memory. Later, when the dots light up again along those lines, the morning comes back.

Why?A single nerve cell remembers nothing on its own. A memory is kept in how strong the connections between cells are. The idea that cells working together become more strongly linked came from the Canadian psychologist Donald Hebb in 1949. In 1973, links that stay stronger for a long time were first seen in a rabbit’s hippocampus.

Go furtherThe board is a small learning memory network with 576 dots. The rice-bowl picture lights up 142 of them, yet storing this one picture changes almost every link on the board a little. A link between nerve cells is called a synapse, and a link staying stronger for a long time is called long-term potentiation.