How is a brain like a train?

Training the brain has been given a whole new meaning, with researchers uncovering a memory-storing system in the brain that works like switchable train tracks.

A team from New York University examined the hippocampus – the part of the brain responsible for memory – of mice and found that it switched to different neural pathways depending on whether it was processing information or recalling a memory.

“Researchers have sought to identify neural circuits that have specialised functions, but there are simply too many tasks the brain performs for each circuit to have its own purpose,”  explains André Fenton of New York University and the senior author of the study, published in Cell Reports.

“Our results reveal how the same circuit takes on more than one function. The brain diverts ‘trains’ of neural activity from encoding our experiences to recalling them, showing that the same circuits have a role in both information processing and in memory.”

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In the experiment, the mice navigated a surface and received a mild shock at certain points, which encoded information in the brain. When the mice returned to the area, they avoided it, remembering the shock.

Using neural activity data from the hippocampus, the researchers found that the hippocampus switched from processing current information to recalling a memory when the mouse got to the shock areas, instead of relying on two separate neural pathways.

Delving deeper, they found this was coordinated by a group of neurons called dentate spikes.

“Railway switches control each train’s destination, whereas dentate spikes switch hippocampus information processing from encoding to recollection,” says Fenton.

“Like a railway switch diverts a train, this dentate spike event diverts thoughts from the present to the past.”