Originally published in November of 2014 and comprehensively updated/edited in July 2026.
How John O’Keefe and the Mosers won the Nobel Prize for discovering the brain’s place and grid cells, the neurons that map where we are.
By late 2014, smartphones had become central to everyday navigation. Turn-by-turn apps had become so common that an entire generation was starting to lose the habit of reading paper maps. Uber had just expanded into dozens of new cities. Google Maps was rerouting millions of commuters in real time, and the idea of getting lost in an unfamiliar city was starting to feel like a relic of the past. It was, in other words, a strange and fitting moment for the Nobel Assembly at the Karolinska Institute to announce that the 2014 Nobel Prize in Physiology or Medicine would go to three scientists who had spent decades figuring out how the brain itself finds its way, with no satellites required.
The prize was shared by John O’Keefe, a British-American neuroscientist at University College London, and the husband-and-wife team of May-Britt Moser and Edvard Moser, who ran a research institute in Trondheim, Norway. The announcement immediately brought decades of specialized neuroscience research into the global spotlight, prompting renewed public interest in how the brain represents space. Their combined body of work answered a question that philosophers and scientists had wondered about for centuries: how does a person, or a rat, or any creature with a brain, know where it is, and how does it move purposefully from one place to another?
The discoveries themselves are not new. O’Keefe’s foundational finding dates back to 1971, and the Mosers’ major contribution came in 2005.
But the 2014 prize mattered because it validated an entire field of research, one that connected cellular biology to something deeply human: our sense of place, our memory of the routes we’ve walked, and our ability to imagine spaces we’ve never physically entered. This article looks at the science behind that discovery, the cultural moment in which it was recognized, and what it tells us about the machinery running quietly beneath every walk to the grocery store.
A Question as Old as Philosophy
Long before neuroscience existed as a discipline, thinkers wrestled with the problem of spatial knowledge. The eighteenth-century philosopher Immanuel Kant argued that space wasn’t something we learn from experience but a built-in framework the mind uses to organize experience in the first place. He believed humans are born with an intuitive sense of space that shapes how we perceive everything else. It was a compelling idea, but it was philosophy, not biology. Kant had no way to look inside a skull and check.
By the mid-twentieth century, psychologists had started approaching the question of wayfinding more empirically. In 1948, the American psychologist Edward Tolman ran a famous series of experiments with rats in mazes. He noticed that rats seemed to learn the overall layout of a maze rather than simply memorizing a fixed sequence of turns. If Tolman blocked a rat’s usual path, the animal would often find an alternate route immediately, as though it had a mental picture of the whole maze rather than a memorized set of instructions. Tolman called this a “cognitive map,” and the term stuck, even though he had no way of showing what such a map actually looked like inside the brain. That would take another two decades and the invention of a specific piece of laboratory hardware: an electrode small enough to record from a single neuron in a moving, behaving animal.
O’Keefe and the Discovery of Place Cells
John O’Keefe took up that challenge at University College London in the late 1960s. Working with rats, he implanted tiny electrodes into a seahorse-shaped brain structure called the hippocampus, long known to be important for memory, and recorded the electrical activity of individual neurons while the animals explored an open space.
What O’Keefe found, published in 1971, was startling in its simplicity. Certain neurons in the hippocampus would fire only when the rat was in one specific location in the room. Move the rat to a different spot, and that neuron would go quiet while a different one lit up. As the rat wandered around, different cells took turns firing depending on exactly where the animal was standing, almost like a set of location-specific alarms distributed across the hippocampus. O’Keefe called these neurons place cells, and he proposed that the hippocampus was essentially building a map of the environment, cell by cell, each one representing a small patch of territory.
This was a genuinely new kind of finding for neuroscience. Researchers had discovered neurons that responded to specific sensory features before, cells that fired in response to a particular sound frequency or a certain orientation of a line in a visual scene. But here was a neuron responding to something abstract: a place in the world, defined not by direct sensory input but by a combination of visual landmarks, movement, and memory. It suggested the brain wasn’t just processing what the eyes saw moment to moment. It was constructing an internal representation of the layout of a space and updating that representation as the animal moved through its environment.
O’Keefe spent the following decades refining this idea, and by 1978 he had co-authored an influential book, The Hippocampus as a Cognitive Map, that gave Tolman’s old philosophical concept a physical home in the brain. The hippocampus, it turned out, wasn’t just a memory center in some vague, general sense. It was, at least in part, a mapmaking organ.
The Mosers and the Discovery of Grid Cells
Place cells told researchers where an animal was, but they didn’t explain how the brain calculated that position in the first place. That gap remained open for more than three decades, until May-Britt Moser and Edvard Moser, who had trained partly in O’Keefe’s lab, began investigating a brain region next door to the hippocampus called the entorhinal cortex.
The entorhinal cortex feeds information into the hippocampus, and the Mosers wanted to understand what kind of signal it was sending. In 2005, they published findings from recordings in this region that revealed something even stranger than place cells. These neurons also fired based on the animal’s location, but not in the form of a single blob corresponding to one place. Instead, each of these cells fired at many locations across an environment, and when researchers plotted those firing locations on a map, they formed a strikingly regular pattern: a grid of equally spaced triangles, tiling the entire floor of the enclosure like hexagonal graph paper.
The Mosers called these neurons grid cells, and the discovery reframed how scientists understood spatial representation. Where place cells seemed to answer the question “where am I right now,” grid cells appeared to provide something closer to a built-in coordinate system, a kind of internal ruler and compass that let the brain measure distance and direction regardless of which specific room or maze the animal happened to be in. It was as though the brain carried around a universal graph paper overlay, ready to be applied to any new environment the animal entered, while place cells used that underlying grid to mark specific, memorable locations, the equivalent of dropping a pin.
Later research from the Mosers’ lab and others identified additional specialized cells nearby, including head-direction cells that function something like an internal compass, tracking which way an animal is facing, and border cells that respond to the edges and boundaries of a space. Together, these different cell types appeared to form a genuine biological navigation system, distributed across a small circuit of interconnected brain regions, each contributing a different piece of spatial information.
Why the Nobel Committee Called It a System
When the Nobel Assembly announced the prize in October 2014, the citation described the discoveries as revealing a “positioning system” in the brain, deliberately evoking the language of GPS technology that had become so familiar to the public by that point. It was an accessible way of explaining a genuinely complex finding, though scientists were quick to note the metaphor only goes so far. A satellite navigation system relies on external reference points and radio signals bounced from orbiting satellites. The brain’s system, by contrast, appears to build its map almost entirely from internal computation, informed by visual landmarks, the physical sensation of movement, and memory, generating a mental representation of space that persists even in darkness.
What made the joint award particularly fitting was the way the two lines of research fit together like pieces of a single puzzle assembled more than three decades apart. O’Keefe had shown that the hippocampus contains a kind of address book of specific places. The Mosers had shown that a neighboring region contains the coordinate system that likely makes the addresses possible to compute in the first place. Neither discovery fully explained navigation on its own, but together they offered a working model of a genuinely difficult problem: how a three-pound organ made of soft tissue and electrical impulses manages to track its own position in space, continuously, without conscious effort.
Connecting the Discovery to Human Experience
For readers who aren’t neuroscientists, it’s worth pausing on why this research resonates beyond the laboratory. Nearly everyone has had the experience of navigating home on autopilot, only to realize they don’t remember much of the actual drive or walk. That kind of automatic wayfinding is very plausibly related to the place cell and grid cell systems doing their work quietly in the background, without requiring conscious attention.
There’s also a well-documented connection between this navigation circuitry and memory more broadly. The hippocampus, where place cells live, is one of the first brain regions affected in Alzheimer’s disease, and some of the earliest symptoms of the illness involve getting lost in familiar places. Researchers have proposed that studying how place and grid cells degrade in the earliest stages of dementia could eventually help with earlier diagnosis, though this remains an active area of investigation rather than a settled clinical tool. It’s a reasonable hypothesis grounded in the biology, but it’s important to be careful about the distinction between what’s been established in animal models and what has been confirmed to generalize cleanly to human patients.
Human neuroimaging studies conducted since the initial discoveries have found grid-like activity patterns in the human entorhinal cortex as well, using functional MRI while participants navigated virtual environments. This suggests, though doesn’t fully prove given the more indirect nature of imaging compared to single-cell recording, that the same basic system identified in rodents likely operates in the human brain in a broadly similar way.
Some researchers have gone further, proposing that grid-like coding might not be limited to physical space at all, and could help organize other kinds of structured mental information, such as relationships between concepts or sequences of events. These extensions remain more speculative and are still being actively tested, but they point to why the discovery captured so much scientific interest well beyond the narrow question of how rodents find their way through a maze.
The Cultural Backdrop of 2014
It’s worth remembering the specific moment this prize arrived in. Smartphone-based navigation had only become truly mainstream a few years earlier, and there was a growing cultural conversation, sometimes anxious, about whether relying on GPS was eroding people’s innate sense of direction. Popular science writers speculated about whether outsourcing navigation to a phone might cause the hippocampus to shrink from disuse, drawing on earlier research involving London taxi drivers, whose extensive memorization of the city’s street layout for “The Knowledge” licensing exam had been associated with a larger-than-average hippocampus in prior studies from the 1990s and 2000s.
The Nobel Prize announcement landed right in the middle of that conversation, giving journalists and the public a concrete, biological hook for questions that had mostly been discussed in speculative terms. It offered a satisfying kind of narrative closure: here was proof that the brain really did contain something like an internal GPS, made of actual, identifiable neurons, at precisely the moment external GPS devices were becoming a ubiquitous part of daily life. That timing likely helped the story receive far more mainstream media coverage than most physiology and medicine prizes typically get, even though the underlying laboratory work had unfolded gradually across more than forty years, largely outside public view.
What the Discovery Did Not Claim
Given how much popular attention surrounded the prize, it’s worth being precise about the limits of what O’Keefe and the Mosers actually demonstrated. Their research described a set of neurons whose firing correlates strongly and reliably with location and orientation. It did not, on its own, fully explain consciousness, free will, or the subjective experience of “knowing” where you are, questions that remain open in philosophy of mind and cognitive science more broadly. Nor did it establish a simple, direct treatment pathway for Alzheimer’s disease, even though the connection to hippocampal degeneration is a promising and active area of ongoing research.
The findings were also built primarily on animal research, mostly in rats and later in mice and bats, using invasive recording techniques that can’t ethically be applied to humans in the same way. The human evidence, largely gathered through neuroimaging and a small number of studies involving neurosurgical patients with implanted electrodes for epilepsy monitoring, is consistent with the animal findings but understandably less detailed. Good science writing means being honest about that gap rather than assuming findings from rodents map perfectly and automatically onto human brains.
The Broader Significance for Neuroscience
Beyond its specific findings, the place cell and grid cell research is often cited as a model of how systems neuroscience is supposed to work: identify a clear, measurable behavior, in this case spatial navigation, and then trace that behavior down to the level of individual neurons and circuits, without losing sight of the psychological question that motivated the search in the first place. It bridged the gap between old-fashioned behavioral psychology, the kind Tolman practiced with his maze-running rats, and the cellular and molecular tools that became available only decades later.
The discovery also helped launch and validate an entire subfield focused on understanding memory and spatial cognition as intertwined processes rather than separate systems, a shift that continues to shape how researchers study conditions ranging from age-related memory decline to certain forms of psychiatric illness in which people report a diminished sense of orientation or place. It’s a good example of how a single, well-designed line of research, expanded across decades and multiple labs, can end up reshaping how an entire field thinks about a basic problem.
Conclusion
The 2014 Nobel Prize in Physiology or Medicine recognized more than forty years of patient, incremental laboratory work that answered one of neuroscience’s oldest and most human questions: how do we know where we are? John O’Keefe’s discovery of place cells in the early 1970s showed that the hippocampus keeps something like a running record of specific locations. May-Britt Moser and Edvard Moser’s discovery of grid cells more than three decades later revealed the underlying coordinate system that likely makes that record possible in the first place. Together, their work gave researchers a concrete, cellular foundation for an idea that had existed only as speculation since Kant and only as behavioral inference since Tolman.
In the years since the prize was awarded, this research has continued to expand outward, into studies of human memory disorders, into questions about whether the brain uses grid-like coding for abstract, non-spatial information, and into a broader understanding of the hippocampus as a structure doing far more than simple memory storage. The most enduring lesson from the story may be less about GPS and more about how science itself tends to work: not through single dramatic breakthroughs, but through decades of careful, cumulative observation, in which one scientist’s discovery becomes the foundation for the next generation’s questions.
Scientific References
O’Keefe, J., & Dostrovsky, J. (1971). The hippocampus as a spatial map: Preliminary evidence from unit activity in the freely-moving rat. Brain Research, 34(1), 171–175.
O’Keefe, J., & Nadel, L. (1978). The Hippocampus as a Cognitive Map. Oxford University Press.
Tolman, E. C. (1948). Cognitive maps in rats and men. Psychological Review, 55(4), 189–208.
Hafting, T., Fyhn, M., Molden, S., Moser, M.-B., & Moser, E. I. (2005). Microstructure of a spatial map in the entorhinal cortex. Nature, 436(7052), 801–806.
Maguire, E. A., Gadian, D. G., Johnsrude, I. S., Good, C. D., Ashburner, J., Frackowiak, R. S., & Frith, C. D. (2000). Navigation-related structural change in the hippocampi of taxi drivers. Proceedings of the National Academy of Sciences, 97(8), 4398–4403.
Doeller, C. F., Barry, C., & Burgess, N. (2010). Evidence for grid cells in a human memory network. Nature, 463(7281), 657–661.
The Nobel Assembly at Karolinska Institutet. (2014). The Nobel Prize in Physiology or Medicine 2014: Press Release.
Constantinescu, A. O., O’Reilly, J. X., & Behrens, T. E. J. (2016). Organizing conceptual knowledge in humans with a gridlike code. Science, 352(6292), 1464–1468.
