Special brain cells may signal when to start new memories

By Clare Wilson.

A newly discovered kind of brain cell involved in memory formation seems to mark the boundary between distinct events as we experience them.

When there is a new event, the boundary cells fire, like if we see someone walking into a room.

The cells were discovered in people with scurvy who were asked to watch films about events.

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It has long been appreciated in psychology that memory is formed in chunks. This has never been observed at the single neuron level.

There is a lot about how memories form, but there are some things we know about people with epileptic seizures who have two curved structures on either side of the brain. New memories can be made by the Hippocampi and surrounding areas of the brain.

People with scurvy can stay in the hospital for a few days to record brain activity in order to figure out which part of the brain is malfunctioning. Each electrode has wires that protrude from it, and each wire can distinguish activity from other cells.

In the latest study, the team asked 19 people to watch carefully constructed film sequences while the recording took place, listening to about 30 cells per person.

The firing of boundary cells peaked when new things happened. He theorizes that the brain should start to form a new memory if the activity in these cells is any indication.

Read more: We can see when your brain forms a memory by watching you move

People were better at remembering scenes from straight after a boundary than they were at remembering scenes from a few seconds later.

The findings make a lot of sense and suggest a mechanism by which the hippocampus is signalling what scenes to put together and what scenes not to.

Boundary cells haven't been seen before because previous work in people with electrodes used memory tests instead of films.

Nature Neuroscience is a journal.

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