New research out of the UK challenges several fundamental assumptions about how memory works, demonstrating that the entire brain is more important to memory than previously understood.
When investigating episodic and semantic memory, researchers from the School of Psychology at the University of Nottingham and the Cognition and Brain Sciences Unit at the University of Cambridge were surprised to find no differences in neural activity between the two.
The researchers published their findings in a recent paper in Nature Human Behavior, in which they analyzed fMRI and task-based data to rethink how our brains store and retrieve information.
Types of Memory
Two primary types of memory were investigated in the research: episodic and semantic. Recalling previous events with their spatial and temporal context is called episodic memory, which is necessary for replaying events in our minds.
Semantic memory refers to our ability to recall words and concepts, essential for reasoning and language. Generally, scientists have believed that these two types of memory are unrelated and that items are likely retrieved through different mechanisms from different parts of the brain.
For the new research, a single group of forty human volunteers was tasked with pairing logos to brand names. Before the task, participants were given a study session to become familiar with the various logos and their associated brands.
Following the memory task, volunteers participated in a debriefing session in which researchers determined whether the subject had preexisting knowledge of the logos. This allowed the researchers to determine whether the recollections were from participants using semantic memory to recall their real-world knowledge, or from participants using episodic memory from the initial study phase.
Designing a Memory Experiment
The Debrief asked lead author Dr Roni Tibon about the decision to use a single set of questions to investigate two types of memory, rather than separate questions targeting episodic and semantic memory.
“This goes to the core of our design choices. Our aim was indeed to match the two tasks as closely as possible in order to minimise potential confounds,” Dr Tibon explained. “To achieve this, participants were required to generate the same type of response in both tasks. In addition, we implemented further matching constraints, such as using unique one-to-one pairings and focusing on a success–failure contrast in both tasks.”
“This design allows us to attribute any observed differences to the memory system being engaged (semantic vs. episodic), rather than to differences in task demands or in how the generated information is used,” Dr Tibon added. “By keeping the question format constant across tasks, we reduce the risk that differences reflect linguistic or strategic factors, while still probing distinct memory systems.”
Monitoring the Brain
While the participants were at work identifying logos, the researchers used functional magnetic resonance imaging (fMRI) to scan their brains. The technique images the brain, revealing how oxygen-rich blood reaches neurons, enabling the creation of 3D maps. By analyzing those maps, researchers can identify changes in blood flow to determine which parts of the brain govern activities such as speaking, moving, and thinking.
“We were very surprised by the results of this study as a long-standing research tradition suggested there would be differences in brain activity with episodic and semantic retrieval,” Dr Tibon said. “But when we used neuroimaging to investigate this alongside the task-based study, we found that the distinction didn’t exist and that there is considerable overlap in the brain regions involved in semantic and episodic retrieval.”
“Our findings suggest that memory in the brain may work less like separate ‘boxes’ for different types of memory, and more like a shared system with many overlapping parts,” Dr Tibon explained. “When people recall personal experiences or general knowledge, they appear to use largely the same brain networks, with differences possibly reflecting the timing or how much certain parts of the system are used rather than completely different systems being switched on.”
Understanding and Treating Memory Issues
“This way of thinking is helpful for understanding brain conditions such as dementia or memory changes in healthy aging, where difficulties rarely fit neatly into one memory category,” Dr Tibon said. “People often show a mix of memory strengths and weaknesses, and these can change depending on the task or the individual.”
Dr Tibon cautions against misreading their findings, noting that this does not mean that all memory is the same, but that there is a carefully balanced system. Understanding this may aid clinicians and researchers in their investigations of changes in memory over time.
To follow up, the team is looking to increase measurement precision by moving from fMRI to Optically Pumped Magnetometer Magnetoencephalography (OPM-MEG), which can capture neural activity at the millisecond scale. This will allow the team to better view how the components of the memory system are engaged over time.
“Importantly, we are combining this approach with more naturalistic memory tasks, where participants speak freely and memory unfolds over time, much as it does in everyday life,” Dr Tibon added.
“This will allow us to study how episodic and semantic memories are retrieved dynamically, offering a more realistic picture of how memory works in real-world settings and how these processes may change across individuals and over time.”
The paper, “Neural Activations and Representations During Episodic Versus Semantic Memory Retrieval,” appeared in Nature Human Behavior on January 26, 2026.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.