Imagine a world where mental disorders could be predicted and even prevented before they fully develop. That's the ambitious goal driving a groundbreaking project: creating the first comprehensive map of the developing human brain. This isn't just about understanding how our brains are wired; it's about unlocking the secrets to conditions like autism, schizophrenia, and ADHD. But here's where it gets controversial: can we ethically intervene in brain development, even if it means potentially preventing these disorders?
Centuries ago, humanity gazed at the moon with a mixture of awe and dread, often attributing sinister influences to it. Then came Johannes Hevelius, a 17th-century astronomer from Gdansk (now in Poland). The son of a wealthy brewer, Hevelius meticulously crafted his own telescope and dedicated countless nights to observing the lunar surface. His efforts culminated in the publication of the first detailed atlas of the moon in 1647, a monumental achievement that paved the way for future lunar exploration.
Now, echoing Hevelius' pioneering spirit, another Gdansk native, Dr. Tomasz Nowakowski, a 40-year-old neuroscientist, is spearheading an equally ambitious endeavor: mapping the human brain from its earliest stages of development in the embryo right through to adulthood. Nowakowski draws a direct parallel: "Humans would never have landed on the Moon if we hadn’t had a map of the lunar surface. All the great advances and achievements in history began with the creation of accurate maps." This brain map aims to be that foundation for understanding and treating mental disorders.
Nowakowski is a key figure in the BRAIN Initiative, a massive U.S. project launched in 2013 by President Barack Obama. With a staggering budget exceeding €4.5 billion ($5.21 billion), the BRAIN Initiative aims to unravel the complexities of the human brain. "The brain, the origin of our thoughts, ideas and imagination, continues to be the most important unexplored object. To understand it, we must start by understanding its list of components," Nowakowski emphasizes.
Think of the brain's development as an incredibly intricate dance. It starts with a single fertilized egg, which multiplies rapidly. From the third week of pregnancy, the rudimentary nervous system begins to form, eventually giving rise to approximately 86 billion neurons and trillions of connections. But sometimes, in this intricate choreography, things go awry. Nowakowski points out that an estimated 15% of children and adolescents grapple with neurodevelopmental disorders such as autism, schizophrenia, or ADHD. And this is the part most people miss: while genetics play a role, environmental factors during development can also significantly impact the brain's trajectory.
The BRAIN Initiative's international consortium is employing cutting-edge technologies to analyze gene activity within individual cells, enabling them to construct a dynamic map of the developing brain. Nowakowski explains the process: "Human tissue can be obtained from surgical procedures or from post-mortem brains that would normally be discarded. If the cells are isolated from the tissue quickly enough, they can be cultured in vitro for a few hours or, in some cases, for several days. This gives us a unique opportunity to study developmental processes in humans." Furthermore, pluripotent stem cells, derived from surplus embryos from fertility clinics or reprogrammed adult cells, allow scientists to replicate the early stages of brain formation in a laboratory setting. This means researchers can now observe and manipulate brain development in ways previously unimaginable.
These advancements represent crucial first steps toward identifying critical periods during pregnancy when the risk of brain tumors or neurodevelopmental abnormalities is highest. Nowakowski notes that genes linked to mental disorders like autism and schizophrenia exhibit heightened activity towards the end of gestation, precisely during the developmental stages that differ most significantly between humans and common laboratory animals like mice. Therefore, having a human-specific atlas is paramount for comprehending the intricacies of human brain formation.
The brain is composed of numerous cell subtypes, each with specialized functions. Neurons are responsible for thinking, astrocytes provide support, oligodendrocytes act as insulation for neural cables, and microglia clear waste from the nervous system. The research consortium has discovered that fetal cells possess remarkable flexibility, capable of transforming into various cell types found in the adult brain. However, this very flexibility also makes them vulnerable. Researchers have identified a progenitor cell type present during the second trimester of pregnancy that can generate neurons, oligodendrocytes, and astrocytes. Intriguingly, a similar progenitor cell is found in glioblastoma, an aggressive brain cancer, offering a potential clue to the tumor's origins.
The BRAIN Initiative Cell Atlas Network recently unveiled the findings of several studies in Nature. The opening lines of the article pay homage to Santiago Ramón y Cajal, the Spanish neuroscientist who, using a microscope and chicken cerebellums, provided the first objective evidence in 1888 that the nervous system is composed of individual cells. "Almost all modern neuroscience is based on the concepts proposed by Cajal," Nowakowski asserts. "He was a visionary, even in areas that we still don’t know how to study. I am convinced that his vision will continue to resonate for many years to come." Cajal's meticulous observations laid the groundwork for our current understanding of the brain's intricate cellular architecture.
Rafael Yuste, another prominent neuroscientist from Columbia University, played a pivotal role in the early stages of the BRAIN Initiative. He recalls a meeting in September 2011 at Chicheley Hall, a British mansion, where two dozen brain experts gathered to discuss potential collaborations. Yuste proposed analyzing all neurons, one by one, arguing that examining only a select few was akin to trying to watch television by looking at a single pixel. While some deemed the idea infeasible, U.S. geneticist George Church, a long-time advocate for comprehensive DNA analysis, declared that in science, "nothing is impossible." The White House embraced the proposal, and in early 2013, President Obama officially launched the project, stating, "As humans, we can identify galaxies light years away, we can study particles smaller than an atom. But we still haven’t unlocked the mystery of the three pounds of matter that sits between our ears."
Yuste is enthusiastic about the initiative's latest findings. "This atlas of developmental cellular types is essential, not just for the scientific understanding of how the brain develops – which is absolutely fascinating when one keeps in mind that it assembles and organizes itself with no external direction – but also, it is fundamental information towards understanding the alterations and pathologies that take place during pregnancy in and in the first stages of life," he says. He further emphasizes the importance of sustained investment in developing and applying new methodologies in science and medicine.
Two years prior, Hongkui Zeng's team presented the most comprehensive map of an adult rodent's brain, a tiny organ containing approximately 70 million neurons and 5,300 cell types. Now, Zeng and his colleagues at the Allen Institute for Brain Science in Seattle have shifted their focus to GABAergic inhibitory neurons, which act as the brain's "brakes," reducing activity to facilitate information transmission. The researchers have discovered that these neurons continue to develop after birth, particularly in brain regions associated with learning, emotions, and decision-making. "This means there could be a longer period than previously thought for intervening and helping the brain to reorganize, especially in the case of children with development disorders," the Allen Institute stated.
Giullermina López Bendito, another neuroscientist, describes the new research as a "qualitative leap" in the field. "Until now, we had cell atlases primarily of adult brains, which provided a static view of cell identity. This collection of articles turns that snapshot into a moving film: it reconstructs the temporal progression and cell lineages that give rise to the developing brain," she explains.
López Bendito leads a laboratory dedicated to understanding the intricate network of connections between brain cells. She highlights that the consortium has mapped various mammalian species, from mice to humans, identifying unique characteristics of humans and other primates, such as the extended period of new neuron generation and the diversification of the cerebral cortex after birth. "These temporal differences could be at the root of both human cognitive abilities and our greater vulnerability to genetic mutations or environmental alterations during development," the neuroscientist notes.
Back in 1888, Santiago Ramón y Cajal embarked on the seemingly impossible task of mapping the brain, millimeter by millimeter, armed only with his microscope. His work culminated in the 1904 publication of "Texture of the Nervous System of Man and the Vertebrates," a monumental 1,800-page work that cautioned that completing the edifice of neurology would still require centuries of effort.
However, Tomasz Nowakowski is more optimistic. "I don’t think we are centuries away, or even decades. I have been impressed by the speed with which artificial intelligence has advanced, especially in recent years, to emulate certain cognitive processes through computational models," he reflects. "I believe we are rapidly approaching a point where theory and modeling will make predictions about which cells and molecules are essential for the structure and function of the brain. And we will have the technologies necessary to test those predictions." This raises a profound question: as we gain the ability to predict and potentially intervene in brain development, what ethical boundaries should we establish? Should we strive to "correct" genetic predispositions to mental disorders, even if it means altering fundamental aspects of human identity? What are your thoughts? Share your opinions in the comments below!
