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A new study shows that the human brain stores what we remember and the context in which it happens using different neurons.
The brain has to do more than store what happened. It also needs to keep track of the circumstances in which an event took place. Scientists in Bonn report that the human brain may handle this by using two distinct sets of neurons, one for content and another for context. Instead of blending both types of information within single cells, the two groups appear to coordinate their activity to build memories. The findings were published in the journal Nature.
People can recognize the same person or object across very different settings, such as a casual dinner with a friend versus a formal meeting with the same friend.
“We already know that deep in the memory centers of the brain, specific cells, called concept neurons, respond to this friend, regardless of the environment in which he appears,” says Prof. Florian Mormann from the Clinic for Epileptology at the UKB, who is also a member of the Transdisciplinary Research Area (TRA) “Life & Health” at the University of Bonn.
For a memory to be useful, though, the brain has to connect that stable content to the situation in which it occurred. In rodents, single neurons often combine both types of information.
“We asked ourselves: Does the human brain function fundamentally differently here? Does it map content and context separately to enable a more flexible memory? And how do these separate pieces of information connect when we need to remember specific content according to context?” says Dr. Marcel Bausch, working group leader at the Department of Epileptology and member of TRA “Life & Health” at the University of Bonn.
Watching the human brain in real time
To test these ideas, the Bonn team recorded the electrical signals of individual neurons in people with drug-resistant epilepsy. As part of clinical diagnosis, electrodes were implanted in the hippocampus and nearby brain regions of these patients – regions that are essential for memory.
During monitoring to determine whether surgery might be an option, participants also chose to complete laptop-based tasks. They viewed pairs of images and compared them using different prompts. For instance, they had to decide whether an item was “bigger” when the trial began with the question “Bigger?”
“This allowed us to observe how the brain processes exactly the same image in different task contexts,” says Mormann.
After examining activity from more than 3,000 neurons, the researchers found evidence for two mostly separate neuron populations. Content neurons responded to particular images (e.g., a biscuit, regardless of the task. Context neurons responded to the task rule or question being asked (e.g., the question “Bigger?”), regardless of which image appeared. Unlike patterns commonly reported in rodents, only a small number of neurons carried both signals at the same time.
“A key finding was that these two independent groups of neurons encoded content and context together and most reliably when the patients solved the task correctly,” says Bausch.
Linking Content and Context
The connections between them strengthened over the course of the experiment: the firing of a content neuron began to predict the activity of a context neuron a few tens of milliseconds later. “It seemed as if the ‘biscuit’ neuron was learning to stimulate the ‘Bigger?’ neuron” says Mormann.
This happens in the sense of a gatekeeper for the flow of information, such that only the relevant context that was previously active is retrieved. This process, known as pattern completion, allows the brain to reconstruct the complete memory context from only partial information.
“This division of labor probably explains the flexibility of human memory: the brain can reuse the same concept in countless new situations without needing a specialized neuron for each individual combination, by storing content and context in separate ‘neural libraries,” says Bausch, and Mormann adds: “The ability of these neuronal groups to link spontaneously allows us to generalize information while preserving the specific details of individual events.”
Although the study used specific questions as interactive contexts on a laptop, there are also other contexts that are passive, such as the room you are in. It remains to be determined whether these everyday background contexts are processed by the same neural mechanisms. In addition, the mechanisms must also be tested outside the clinical setting. An important next step will be to investigate whether deliberately disrupting the interaction between these neurons prevents a person from retrieving the correct memory in context or making the right decision.
Reference: “Distinct neuronal populations in the human brain combine content and context” by Marcel Bausch, Johannes Niediek, Thomas P. Reber, Sina Mackay, Jan Boström, Christian E. Elger and Florian Mormann, 7 January 2026, Nature.
DOI: 10.1038/s41586-025-09910-2
The study was funded by the DFG, the Volkswagen Foundation, and the NRW joint project “iBehave.”
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