Small talk is one of most people’s favorite pastimes. But it’s also a favorite activity of the different regions of our brain, which “converse” continuously and in a coordinated fashion so that we are able not only to chat, but also to see, walk, smell, eat, read, think, make decisions, and remember, in short, to be human and function as such.
As the first atlas of the so-called “functional architecture” of the brain, that is, the organization of how it operates, now reveals, the communication patterns between its different regions change from the first day of life all the way to age 100. This is the first time such patterns have been “mapped,” thanks to a new guide with the “blueprints” of brain function from cradle to deep old age, recently published in the scientific journal Nature.
Identifying Patterns
To create this detailed atlas of the brain’s “conversations,” the research team analyzed a total of 3,972 brain scans from 3,556 individuals — ranging from newborns to centenarians — drawn from five large imaging studies. The material was produced using an advanced imaging technique called resting-state functional MRI (resting-state fMRI), which is used to study communication between different brain regions while the subject is awake but not performing any specific mental or motor task.
This technique measures small changes in blood oxygen levels in the brain, which reflect brain activity. The fact that subjects are simply resting inside the MRI scanner allows researchers to observe the brain’s inherent functional organization.
The data on inter-regional brain communication was then converted into patterns that revealed the gradations of the brain’s functional connectivity, that is, its functional organization, not merely its fixed anatomical structure. The study’s first author, Hoyt Patrick Taylor, a postdoctoral researcher in the Department of Radiology at UNC–Chapel Hill, explained: “Just as doctors use growth curves to track height and weight over time, we followed a similar philosophy to map how different brain regions communicate with each other at every stage of life. The ultimate goal of this analysis is to better understand how brain function ‘unfolds’ from development through aging, and how this picture may differ in cases of disease.”
Axes of Functionality
In the brain, even two regions that are far apart from each other may be active at the same time, indicating that they cooperate to support the same function. The UNC team sought to “decode” precisely this functional connectivity between different regions. To do so, the scientists examined brain regions along three key axes, derived from their connectivity patterns, as explained by the study’s senior author, Pew Tian Yap, Professor of Radiology, Biomedical Engineering, and Computer Science at UNC–Chapel Hill.
“Points at the top of each axis corresponded to regions involved in complex processes such as abstract thinking, while points at the bottom involved areas dedicated to basic sensory processing, such as vision or touch — the communication patterns between regions across different axes also reflected their connectivity profiles. Using this system, anyone looking at the atlas can quickly see which brain regions work together and how their coordination changes over time.”
Previous studies by other groups had revealed changes in the brain’s functional architecture at isolated stages of human life, but this is the first time an atlas has been created that encompasses the evolution of all three functional axes across the entire human lifespan, Professor Yap noted. “And this is critically important for fully understanding how the human brain works.”
Changes Over Time
This meticulous work revealed that each axis follows its own developmental trajectory from the cradle to deep old age. For example, the contrast in connectivity between regions at either end of the axis linking sensory functions to higher associative functions becomes more pronounced during childhood and adolescence, reaching its peak around age 19.
“This differentiation reflects the maturation of the young brain toward a more ‘adult’ organization,” Dr. Taylor explained, adding that the team was surprised by how closely each individual’s brain organization correlates with their cognitive performance. “We found that young adults whose sensory-to-associative axis followed the patterns seen in the population average had better cognitive performance, meaning their information processing speed and memory were overall better than those of young adults whose brain activity patterns deviated from the average.”
The analysis also revealed that a separate axis, relating to brain regions involved in cognitive control and the formation of mental representations of information, is linked to the early development of motor skills, suggesting, in Dr. Taylor’s words, “that different functional brain patterns take center stage at different life stages.”
The study also found that the most dramatic restructuring of brain function occurs during the first four years of life. “In this period, basic sensory and motor systems dominate the brain. As the child grows and matures, the hierarchy shifts and the regions responsible for complex thought become more distinct and specialized. As a person moves toward the twilight of life, the sharp differences between brain regions begin to diminish, meaning the brain loses its specialization as it ages. At the same time, in the aging brain, the patterns related to sensory processing become far weaker, that is, the processes linked to the body’s basic functions gradually fade,” Professor Yap emphasized. In short: we begin life with the simple, progress to the complex, and return to the simple toward the end (though unfortunately, by then even the simple becomes… complex!).
Decoding “brain conversations” is a difficult research path, but one that holds hope for one day preventing serious diseases, both researchers confirmed they are continuing their work in this direction, so that more and more brains can remain… talkative (with meaningful content).
The Wonderful World of the Mind
The human brain is extraordinarily complex and truly remarkable. Here are some brain facts that may surprise you:
- Its average weight is about 1,400 grams.
- Albert Einstein’s brain weighed 1,230 grams, 10% smaller than average, but with a higher density of neurons.
- The male brain is about 10% larger than the female brain, however, the hippocampus, considered the brain’s memory center, is larger in women.
- Although humans have the largest brain relative to body weight in the animal kingdom, they don’t have the largest brain of all species, that record belongs to the sperm whale, whose brain weighs nearly 8 kilograms.
- The human brain has shrunk over the past 10,000–20,000 years, losing a volume roughly the size of a tennis ball.
- The brain is 60% fat by dry weight, making it the body’s fattiest organ.
- It runs on 12–25 watts of electricity, enough to power an LED light bulb.
- It consumes 20% of the body’s energy, despite accounting for only 2% of total body weight.
- It contains roughly 100 billion neurons and up to 1 quadrillion synapses (the junctions where signals pass between neurons).
- Nerve signals travel at speeds of over 550 km/h — far faster than a Formula 1 car.
- There are approximately 10,000 different types of neurons in the brain.
- It is a myth that we use only 10% of our brain. We use the entire brain, even while sleeping, it never fully rests.
- The brain is estimated to generate around 50,000–70,000 thoughts per day.
- Babies have large heads to accommodate their rapidly growing brains. A two-year-old’s brain is already at 80% of its adult size.
- Our attention span is shrinking. In 2000 it averaged 12 seconds; now it is just 8 seconds, less than the 9-second attention span of a goldfish.
