How brain creates signposts and remember them too

Placing a pin in the google map to mark a place is one thing and creating signposts in the brain is quite another. But scientists have now discovered that our brain may just do something similar as the place cells in the brain can also act like neural flags that "mark" an experience on the cognitive map.

A place cell is a type of neuron within the hippocampus that becomes active when an animal or human enters a particular place in its environment.

The hippocampus is the brain's warehouse for long- and short-term processing of episodic memories, such as memories of a specific experience like a trip to place or a recent dinner.

While studying brain activity of rodents, a team of scientists noticed that the rats frequently paused to inspect their environment with head movements as they ran.

The scientists found that this behaviour activated a place cell in their brain, which helps the animal construct a cognitive map, a pattern of activity in the brain that reflects the animal's internal representation of its environment.

The researchers found that when the rodents passed that same area of the track seconds later, place cells fired again, a neural acknowledgement that the moment has imprinted itself in the brain's cognitive map in the hippocampus.

"This is like seeing the brain form memory traces in real time," said James Knierim, professor of neuroscience at Johns Hopkins University.

"Seeing for the first time the brain creating a spatial firing field tied to a specific behavioural experience suggests that the map can be updated rapidly and robustly to lay down a memory of that experience," he said.

In the experiments, researchers placed tiny wires in the brains of the rats to monitor when and where brain activity increased as they moved along the track in search of chocolate rewards.

"There are strong indications that humans and rats share the same spatial mapping functions of the hippocampus, and that these maps are intimately related to how we organise and store our memories of prior life events," Knierim said.

The study appeared in the journal Nature Neuroscience.