Neuroscientists uncover fast-learning way that allows brain to rewire in seconds

Neuroscientists have identified a newly described form of neuroplasticity—the brain’s ability to be reshaped by experience—that may allow learning to occur over the span of several seconds, long enough to capture the full process of learning from a single event.

In two recent reviews published in The Journal of Neuroscience and Nature Neuroscience, researchers describe this mechanism as “behavioural timescale synaptic plasticity,” or BTSP. 

Scientists believe it may enable the brain to learn from a single exposure, as reported in an article by Quanta Magazine.

It operates in the hippocampus, the brain’s memory centre, and is triggered by electrical changes that affect multiple neurons simultaneously over a timescale of several seconds.

The brain is “incredibly plastic, and it stays that way throughout the lifespan of a human,” said Christine Grienberger, a neuroscientist at Brandeis University in Boston, Massachusetts.

This adaptability—the capacity to be reshaped—underpins the brain’s extraordinary learning abilities, from remembering the plot of a novel and navigating unfamiliar cities to acquiring new languages or avoiding a hot stove. Yet neuroscientists are still working to uncover the fundamental rules that govern how these changes occur.

By identifying BTSP, researchers have added a new piece to the puzzle of how the brain is modified by experience, bringing science closer to a full account of how learning works. “Neuroplasticity is … one of the last frontiers of the brain,” said Attila Losonczy, a neuroscientist at the University of Texas Southwestern Medical Center who studies BTSP. “If we understand this, I think we take a major step towards understanding how the brain works.”

For much of neuroscience’s 150-year history, however, the adult brain was believed to be fixed and unchanging. “The idea that the adult brain can change wasn’t actually widely accepted until very late [in] the history of modern neuroscience,” said Moheb Costandi, neuroscientist and author of Neuroplasticity (MIT Press). “It was taken for granted that the adult human brain can’t change.”

The effects of neuroplasticity are perhaps most strikingly illustrated in clinical case studies. One patient born without an olfactory bulb was still able to smell because other brain regions reorganised to take over that function. Another patient had the entire left hemisphere removed as a child, yet the right hemisphere adapted to assume many of its roles, allowing for a functional adult life. Similarly, after stroke or traumatic injury, surviving neurons can reorganise to restore abilities such as speech and movement.

Neuroplasticity also underlies everyday learning, which is primarily thought to occur through synaptic plasticity—changes in the trillions of connections between neurons. For more than 70 years, the dominant explanation has been Hebbian plasticity.

But neuroscientists “always had a sneaking suspicion that Hebbian plasticity wasn’t quite right,” said Jeffrey Magee, a neuroscientist at Baylor College of Medicine. Or at least, not the full picture. Hebbian theory requires repeated experience to strengthen neural connections, which explains gradual learning such as acquiring a language, but struggles to account for rapid learning from a single intense event—like touching a hot stove.

BTSP initially faced scepticism within the field, Magee noted, because it challenged long-standing assumptions about how learning works. However, in recent years, growing experimental evidence has led more researchers to explore its validity.

The method may also help solve a longstanding neuroscience puzzle. Because it selectively strengthens only the neurons relevant to a specific experience, rather than all active neurons, it may address the “credit assignment problem”—how the brain determines which cells should store a particular memory.

Researchers, including Magee, are now investigating whether BTSP plays a role not only in learning but also in the consolidation of memories.

By Nazrin Sadigova