For decades, neuroscientists have operated under a compelling assumption: the brain’s extraordinary capabilities arise primarily from the intricate web of connections between neurons.
This “connectionist” view has dominated brain research, driving ambitious projects like the Human Connectome Project, which has mapped the neural highways of the human brain in unprecedented detail. But what if we’ve been looking in the wrong place all along?
A groundbreaking study is challenging this long-held orthodoxy, suggesting that the brain’s physical shape—its geometry and contours—may be far more important than the complex wiring between its regions.
This paradigm-shifting research doesn’t merely tweak our understanding of brain function; it fundamentally reimagines how we think about the organ that makes us who we are.
The Connectome Era
To understand why this new research is so revolutionary, we first need to appreciate the dominance of the connectionist paradigm.
For the better part of the last century, neuroscience has been captivated by the idea that the brain operates like an extraordinarily sophisticated computer network.
In this view, neurons are nodes, and the synaptic connections between them are the wires that transmit information. The pattern of these connections—the connectome—was thought to hold the key to understanding everything from memory and learning to consciousness itself.
This perspective has yielded remarkable insights. We’ve learned how different brain regions communicate with each other, identified neural circuits involved in specific behaviors, and even begun to understand how disruptions in connectivity might contribute to disorders like schizophrenia and autism.
Billions of dollars and countless research hours have been invested in mapping these neural connections with ever-greater precision.
The logic seemed impeccable: if we could just map all the connections, we could decode the brain’s operating system. After all, doesn’t a computer’s functionality emerge from how its components are wired together? Shouldn’t the same principle apply to the three-pound universe inside our skulls?
A New Geometric Perspective
Enter the latest research that’s turning this assumption on its head. Scientists have now demonstrated that the brain’s shape—its physical geometry and the spatial arrangement of its structures—may actually be the primary driver of brain activity patterns, with connectivity playing a surprisingly secondary role.
The study employed advanced neuroimaging techniques and computational models to analyze brain activity across different states and tasks.
What researchers discovered was both surprising and profound: patterns of brain activity could be predicted with remarkable accuracy based solely on the brain’s geometric properties—its folds, curves, and spatial organization—even when connection information was excluded from the models.
When the reverse was attempted—predicting activity patterns using only connectivity data without geometric information—the models performed significantly worse.
This wasn’t a marginal difference; the geometric models consistently outperformed connectivity-based models across various measures of brain function.
The Physics of Brain Waves
So how exactly does shape trump wiring? The answer lies in the physics of how brain waves propagate through neural tissue. Think of the brain not as a computer network, but as a three-dimensional medium through which waves of activity flow, much like ripples spreading across a pond or sound waves moving through air.
The brain’s geometry acts like the landscape through which these waves travel. Just as hills, valleys, and obstacles shape how sound or water waves move, the folds of the cortex, the curves of neural structures, and the spatial relationships between brain regions fundamentally influence how neural activity patterns emerge and evolve.
This wave-like perspective reveals that the brain may operate more like a resonating chamber than a circuit board. The gyri and sulci—the characteristic ridges and grooves of the brain’s surface—aren’t just packaging solutions to fit more neural tissue into a confined skull. They’re functional features that shape the flow of neural activity itself.
When a region of the brain becomes active, that activity doesn’t just travel along pre-defined neural pathways like electricity through a wire. Instead, it spreads through the neural tissue in wave-like patterns that are channeled, reflected, and modulated by the brain’s physical architecture.
The geometry acts as a kind of waveguide, determining where activity goes, how it combines with other activity patterns, and ultimately what computations the brain can perform.
Rethinking Neural Communication
This geometric view also challenges our understanding of how different brain regions communicate. The traditional model suggested that regions talk to each other primarily through direct anatomical connections—like two cities connected by a highway.
But the new research suggests that regions might also communicate through the spatial propagation of activity patterns—more like how sound can travel between rooms not just through doorways, but through the very structure of a building.
This doesn’t mean that neural connections are irrelevant. The synaptic links between neurons clearly matter for many aspects of brain function. But perhaps they’ve been assigned too much explanatory weight.
The new findings suggest that connectivity might be more like the plumbing in a building—necessary for the system to work, but not the primary determinant of the building’s functionality. The architecture—the shape and spatial organization—may be what really matters.
Implications for Evolution and Development
If brain shape is indeed paramount, this has profound implications for how we understand brain evolution and development. The human brain’s distinctive shape—with its extensive folding and particular proportions—might not just be an evolutionary response to the need for more neurons.
Instead, these geometric features might have been directly selected for their functional properties, their ability to support particular patterns of neural activity that enable human cognition.
During development, we know that the brain’s shape emerges through a complex choreography of genetic programs and mechanical forces.
Brain regions grow at different rates, tissue folds under physical constraints, and structures take their final form through processes that are as much physical as they are purely biological.
If geometry is functionally primary, then these developmental processes aren’t just creating a scaffold for neural connections; they’re directly building cognitive capabilities into the brain’s very structure.
This also suggests new ways to think about individual differences in cognitive abilities. Rather than focusing exclusively on differences in how brains are wired, we might need to pay more attention to subtle variations in brain geometry.
Perhaps differences in the depth of certain folds, the curvature of specific structures, or the spatial relationships between regions contribute more to cognitive variation than differences in connection strength.
Clinical and Therapeutic Implications
The therapeutic implications of this geometric perspective are potentially transformative. If brain shape is a primary determinant of function, then techniques that can modify or work with brain geometry might be more powerful than we realized.
Consider, for example, transcranial magnetic stimulation (TMS), a technique that uses magnetic fields to stimulate brain activity.
Current TMS protocols are often guided by assumptions about connectivity—we target certain regions because of their connections to other areas involved in depression, for instance. But a geometry-first approach might suggest entirely different targeting strategies, focusing on how stimulation will propagate through the brain’s geometric landscape.
Similarly, understanding neurological and psychiatric disorders might require new geometric perspectives.
Could the cognitive symptoms of Alzheimer’s disease arise not just from dying neurons and broken connections, but from the way brain atrophy changes the geometry through which neural activity propagates? Might the symptoms of conditions like epilepsy or migraines be better understood as disturbances in the geometric propagation of neural waves?
Even surgical interventions might need to be reconsidered. Neurosurgeons work hard to preserve functional tissue and important connections, but perhaps the geometric consequences of surgery—how removing a tumor changes the shape of surrounding tissue—deserve more attention than they’ve received.
Technological Applications
Beyond medicine, this geometric understanding of brain function opens new avenues for brain-inspired technology.
Current artificial neural networks are explicitly based on the connectionist model—they’re all about connections between nodes, with little attention paid to spatial geometry. But what if we designed AI systems that incorporate geometric principles?
Such systems might be fundamentally different from current deep learning architectures. Instead of focusing solely on connection weights and network topology, we might create systems where information propagates through virtual geometric spaces, where the “shape” of the computational medium matters as much as the connections within it.
Brain-computer interfaces, too, might benefit from geometric insights. If we want to read out neural activity or write information into the brain, understanding how activity propagates geometrically through neural tissue could lead to more effective and naturalistic interfaces.
Challenges and Questions
Of course, revolutionary findings always invite scrutiny, and this geometric perspective raises important questions.
How exactly do we define and measure brain geometry in ways that capture the features most relevant to function? The brain is a dizzyingly complex three-dimensional structure; determining which geometric features matter most is no simple task.
Moreover, the relationship between geometry and connectivity isn’t likely to be simply either-or. These two aspects of brain organization surely interact in complex ways.
The challenge ahead is to understand precisely how they work together, and under what circumstances each plays a more dominant role.
There are also questions about causality. Does brain shape directly cause activity patterns, or might both emerge from deeper organizing principles? Could it be that the same developmental and evolutionary forces that shape brain geometry also influence connectivity patterns, creating a correlation between the two that doesn’t necessarily imply that geometry is causally primary?
A Paradigm in Transition
Scientific paradigms rarely shift overnight. Thomas Kuhn, in his classic analysis of scientific revolutions, noted that established frameworks are remarkably resilient, often persisting until a critical mass of anomalies accumulates and a new generation of scientists embraces alternative perspectives.
The connectionist view of the brain is deeply entrenched, supported by decades of research and enormous institutional investment.
Yet the geometric perspective offers something that every powerful scientific theory must provide: it explains existing observations, makes novel predictions, and opens up new avenues for investigation. As more researchers explore this geometric framework, we’ll discover whether it can deliver on its revolutionary promise.
What’s particularly exciting is that we’re living through this potential paradigm shift. The tools to test geometric hypotheses—advanced neuroimaging, computational modeling, and sophisticated analytical techniques—are rapidly improving.
The next few years will likely bring a flood of studies exploring how brain geometry influences function across different species, developmental stages, and cognitive states.
Conclusion: Reshaping Our Understanding
The suggestion that brain shape matters more than brain wiring is more than just an academic curiosity. It represents a fundamental reconceptualization of what the brain is and how it works.
If true, it means that the three-dimensional, physical brain—the actual organ with its folds, curves, and contours—is not just a biological substrate for abstract neural networks, but is itself a functional feature of immense importance.
This perspective invites us to think about brains as physical objects subject to the laws of physics, not just as information-processing networks. It suggests that evolution has sculpted not just the pattern of connections in our brains, but the very landscape through which our thoughts flow.
Perhaps most profoundly, this geometric view reconnects us with the physical reality of the brain. In an age when we often think of minds as software that might someday run on any substrate, the geometric perspective reminds us that our thoughts and experiences are inextricably tied to the particular physical organ in our heads, with its unique shape forged by millions of years of evolution and months of prenatal development.
We may indeed have gotten the brain wrong, or at least incomplete. But that’s not a failure of neuroscience—it’s exactly how science progresses.
Each generation of researchers builds on and sometimes overturns the assumptions of the previous generation, getting closer to understanding the most complex object we know of in the universe: the human brain. If the shape of that understanding is now changing, perhaps it’s because we’ve finally recognized that shape itself has been the key all along.
