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BARCELONA — For the first time, scientists have confirmed that the human brain processes memories in a way that’s remarkably different from other species — a finding that may reveal a key foundation of human intelligence. Their research shows that individual neurons in the human brain represent concepts consistently, regardless of the context in which we encounter them. It’s a stark contrast to what happens in the brains of rodents and monkeys.

This finding may help explain some uniquely human cognitive abilities, including our capacity for abstract thought, metacognition, and forming connections across vastly different situations. It indicates that the way our brains encode memories might be a key evolutionary adaptation that separates the human mind from that of other species.

“This context-invariant coding could be a key, unique feature of human intelligence,” the researchers note in their paper.

More specifically, the study, published in Cell Reports, suggests this ability to maintain stable neural representations across different situations may be what enables our unique capacity for abstract thinking.

“The basic principle of neuronal coding in humans is the opposite of what has been observed in other species, which has significant implications,” notes Dr. Rodrigo Quian Quiroga, who led the research at the Hospital del Mar Research Institute, in a statement. This fundamentally different approach to memory storage represents a radical departure from existing neuroscience models.

Why Neuronal Behavior Matters

The research team studied the activity of individual neurons in the brains of nine epilepsy patients who had electrodes implanted as part of their treatment. This rare opportunity allowed the scientists to observe how single neurons behave when forming and recalling memories—something that cannot be done with standard brain imaging techniques.

The study revealed something unexpected: When a neuron responded to a specific person (like the Argentinian TV host Diego Topa used in one example), it fired in almost exactly the same way regardless of whether that person appeared in story context A or story context B. This contradicts decades of animal research showing that neurons in other species significantly modify their firing patterns based on context.

When a rat encounters a familiar object in two different locations, its brain activates different sets of neurons—essentially creating separate memories for the same object in different contexts. This has been well-documented across animal studies.

Human brains, however, appear to work differently. Our neurons recognize concepts consistently, regardless of where we encounter them. It’s as though our brains prioritize the “what” over the “where” or “when.”

How the Study Worked

The researchers used a clever experimental design to investigate this phenomenon. Patients learned and recalled four simple stories, with two different stories featuring the same person in entirely different contexts. By recording the activity of individual neurons as participants learned and recalled these stories, the scientists could directly observe how context influenced neural responses.

Incredibly, nearly all neurons (97% during encoding and 100% during recall) maintained consistent firing patterns regardless of which story context was being processed. The neurons fired robustly to the presence of a specific person regardless of where they appeared in the narrative.

This consistency held true across different tasks as well. The same neurons activated whether participants were passively viewing images of people, actively learning stories about them, or recalling those stories from memory.

The researchers also looked for evidence of “conjunctive coding”—neurons that might fire only to specific combinations, such as “Jackie Chan at the waterfall” but not “Jackie Chan at another location.” Such conjunctive coding is common in animal studies but was almost entirely absent in the human participants. Less than 1% of neurons showed any evidence of responding to specific person-context combinations.

Statistical models built by the team could successfully predict which person a participant was processing but failed to predict which specific story context was involved—further evidence that the neural representations were context-independent.

A New Perspective of Human Intelligence

“Memories are stored in a much more abstract manner in humans compared to other animals. You can think of concepts or anything else in more abstract terms, independent of the context in which you learned them,” explains Dr. Quian Quiroga, suggesting that this could be one of the “foundations of human intelligence.”

This ability to maintain consistent mental representations across different contexts might be what enables humans to think abstractly and make connections between seemingly unrelated scenarios.

“This ability allows us to make much more abstract and complex associations and inferences than if we were forced to think of each concept within a specific, concrete context,” Dr. Quian Quiroga asserts. “In other words, humans can decontextualize their memories to create more abstract thought.”

These findings challenge the prevailing view that human memory works similarly to that of other mammals, just with greater complexity. Instead, they point to a key difference in information processing that could help explain uniquely human cognitive abilities.

This mechanism might be what allows us to recognize the same person in completely different contexts, take lessons learned in one domain and apply them to entirely different scenarios, or understand abstract concepts like justice or democracy regardless of the specific examples we encounter.

The human brain, it seems, plays by different rules than we’ve long believed—rules that might help explain our unique place in the animal kingdom.