Brain study reveals memory types share deeper overlap than thought

For decades, neuroscientists have treated episodic memory — your recollection of that conversation last Tuesday — and semantic memory — your knowledge that Paris is the capital of France — as fundamentally separate systems in the brain. A new study from researchers at the University of Nottingham and Cambridge suggests that assumption might be wrong.

When scientists at these institutions scanned the brains of 40 people retrieving different types of memories, they found something unexpected: the same brain regions lit up whether someone was recalling a personal experience or retrieving a fact. The distinction that has shaped memory research for decades appears far less clear-cut than anyone thought.

"We were very surprised," says Dr. Roni Tibon, who led the research. "A long-standing research tradition suggested there would be differences in brain activity with episodic and semantic retrieval. But when we used neuroimaging to investigate this, we found that the distinction didn't exist and that there is considerable overlap in the brain regions involved."

How they tested it

The team designed a clever experiment to compare apples to apples. They showed 40 participants pairings between logos and brand names. Some pairings drew on real-world knowledge people already had (the semantic task), while others were pairs they'd learned moments earlier in the lab (the episodic task). Using fMRI — a brain imaging technique that tracks blood flow to see which areas are active — researchers watched what happened in the brain as people retrieved each type of memory.

The results were remarkably similar. Whether someone was pulling up a fact or reliving a moment, the same overlapping brain regions were engaged. Any differences the researchers detected were subtle enough that they didn't support the traditional model of separate memory systems.

This matters because it reframes how scientists should think about memory itself. For years, the field has studied episodic and semantic memory in isolation, treating them as distinct categories with distinct neural machinery. If they actually share the same underlying systems, researchers have been asking the wrong questions.

"These results should change the direction of travel for this area of research," Tibon says, "and hopefully open up new interest in looking at both sides of memory and how they work together."

Why this could matter for disease

The implications extend beyond pure neuroscience. Understanding that memory retrieval engages the whole brain — not isolated pockets — could reshape how researchers approach memory-related diseases like Alzheimer's and dementia. If interventions are developed with this integrated view in mind, they might be more effective than approaches targeting single brain regions.

The study, published in Nature Human Behaviour in January 2025, represents the kind of research that quietly upends decades of assumptions. It's a reminder that even well-established frameworks in science can shift when someone bothers to test them carefully. The next phase of memory research will likely look quite different from what came before.