For many years, scientists have believed that our experiences, emotions, and behaviors are shaped by a complex network of connections in our brains. This network, composed of trillions of cells, allows different regions of the brain to communicate with each other.
This intricate web of communication is often seen as the foundation of our thinking, feeling, and behaving – essentially, our consciousness.
However, a groundbreaking study led by researchers from Monash University’s Turner Institute for Brain and Mental Health is challenging this well-established perspective.
In a significant departure from traditional thought, their research points towards the physical shape of our brains as a more critical influence on our mental and emotional lives than the web of neuronal connections.
A New Way to Look at the Brain
Think of the brain as a very intricate piece of clay. Traditionally, we’ve been focusing on the marks and lines on its surface, tracing out the complex networks formed by billions of neurons. But what if the shape of the clay itself, the physical form of the brain, had a more significant role in determining how it functions?
This new way of thinking about the brain is the essence of the study conducted by the team at Monash University’s Turner Institute. Instead of focusing solely on the vast neural network within our brains, they propose that the overall shape of our brain could be a more vital factor in determining our thoughts, feelings, and behaviors.
To make this determination, the researchers didn’t just examine a handful of brain scans. They analyzed a colossal amount of data, more than 10,000 different maps of human brain activity. This vast and diverse dataset gave them a comprehensive view of how our brains work, leading to this potentially paradigm-shifting discovery.
The Role of Eigenmodes in Understanding Brain Function
Before we dive deeper into the study, let’s simplify a complex term: eigenmodes. In the most basic terms, an eigenmode refers to the unique patterns that occur when something vibrates or resonates – think of the different sounds you get from a guitar string when you strum it. For our brains, eigenmodes are kind of like the “notes” our brain plays when it thinks, feels, and reacts.
Eigenmodes and the Brain
Now, what does a term from physics have to do with neuroscience? It turns out, quite a lot. In this study, the researchers used magnetic resonance imaging (MRI) to study the eigenmodes of the brain. By looking at these patterns of vibrations or resonations, they gained a new perspective on how brain activity occurs.
This approach is relatively new in the field of brain study. It moves the focus from the complex connectivity among different regions of the brain to the shape of the brain itself, thereby simplifying our understanding of brain function.
The Impact of Brain Shape
So, how exactly does the shape of the brain influence its function? To understand this, consider a drum. The sound a drum produces depends heavily on its shape. Similarly, the Monash University researchers found that the shapes and curves of our brain, its geometric structure, are strongly linked to how it functions.
By comparing how well eigenmodes from brain shape models could explain brain activity patterns against those obtained from models of brain connectivity, they found an interesting result. The geometric eigenmodes – those derived from the brain’s shape – provided a much stronger explanation for the observed brain activity.
This surprising discovery brings a fresh perspective to our understanding of the brain, and its implications could be wide-ranging.
Shifting Our Understanding of Brain Activity
Traditionally, we’ve believed that certain thoughts or sensations ignite activity in specific parts of our brains, much like flicking on a light switch in a room. However, this research challenges that belief, suggesting that our brain activity is not so localized after all.
Imagine dropping a pebble into a pond. The impact doesn’t just create a single, isolated ripple. It creates a series of waves that spread across the entire pond. Similarly, this study proposes that our brain activity is more like these spreading ripples, with the structure of our “brain pond” influencing the patterns of these ripples.
To back up this idea, the research team found that across the 10,000 MRI activity maps they studied, the activity patterns were dominated by eigenmodes that extended over long distances, exceeding 40 mm.
This new understanding suggests that traditional brain mapping methods, which focus on specific areas of activity, may only be scratching the surface of how our brains truly work.
Predicting Brain Function from Its Shape
This research doesn’t just change our understanding of how the brain functions, it also opens up exciting new possibilities for future research and applications. By establishing a link between the shape of our brains and their function, there’s potential for developing ways to predict brain function based purely on its shape.
This could pave the way for exploring how the brain contributes to individual differences in behavior and even risk for psychiatric and neurological diseases. For instance, we might be able to understand the effects of conditions like dementia and stroke better by considering models of brain shape, which are simpler to work with than models of the brain’s full array of connections.
This study from the Turner Institute represents a significant leap in our understanding of the human brain. By shifting the focus from complex neuronal connectivity to the shape of the brain itself, it provides a simpler yet powerful framework for understanding how our brain functions, develops, and ages.
The implications of this could be far-reaching, impacting everything from our understanding of individual behavior to the way we approach neurological and psychiatric diseases. As we delve deeper into the fascinating world of neuroscience, it’s exciting to imagine what other paradigm-shifting discoveries await us.
Pang, J.C., Aquino, K.M., Oldehinkel, M. et al. Geometric constraints on human brain function. Nature 618, 566–574 (2023). https://doi.org/10.1038/s41586-023-06098-1