From a Milan conference to modern neuroscience, the journey to decipher the chemistry that builds our brains
What if the very essence of who you are—your thoughts, memories, and talents—is written not in the stars, but in the intricate chemistry of your developing brain?
This profound question lies at the heart of a scientific quest that was boldly advanced one September in 1970, when leading researchers gathered in Milan to unravel the mysteries of the brain's chemical blueprint. For centuries, the brain was a black box, but a revolution was brewing—one that would shift the focus from its mysterious folds to the invisible molecular maelstrom within. This is the story of how chemistry builds the human experience, transforming a fragile embryo into a thinking, feeling being.
In September 1970, the Advanced Study Institute on "Chemistry of Brain Development" convened in Milan, Italy. This was not merely another academic conference. As the proceedings volume editor noted, it was born from a crucial realization: The development of the central nervous system is possibly the most significant aspect of the growth of a mammal from embryo to adulthood 1 2 .
The scientists argued that the "engrams" that form the basis of our individual characteristics—the physical traces of our memories and personality—are laid down mainly in the central nervous system during its growth 1 2 .
However, they championed a revolutionary, integrated approach. The chemical events of brain development could not be understood in isolation. They had to be studied "in full awareness of the concomitant morphological, physiological and psychological events" 1 2 . This multidisciplinary spirit, weaving together different strands of science, became the guiding principle for unlocking the brain's chemical secrets.
So, what exactly is happening behind the scenes? The development of the brain is a long trajectory, beginning within a few days after conception and continuing through adolescence and beyond 8 . It is an elaborate symphony of processes, orchestrated by both genes and environment.
The brain begins as a simple neural plate, which folds into the neural tube 8 . This tube becomes the brain and spinal cord. Cells then divide rapidly, and new neurons migrate to their precise destinations, forming the basic architecture of the brain.
Once in place, neurons undergo a phenomenal change. They sprout axons and dendrites, like tiny branches reaching out to connect with one another. The points of communication they form are called synapses 8 . This process, synaptogenesis, explodes in early life, creating a super-dense network of connections.
A surprising thing happens after this initial burst of connection-building. The brain begins to eliminate synapses in a process called pruning 8 . This isn't a sign of decay, but of refinement. The connections that are used are strengthened and retained, while those that are not used are eliminated. This fine-tunes the brain's circuitry based on experience, making it more efficient.
Underpinning all these structural changes is a complex neurochemistry—the signaling of neurotransmitters and the support of glial cells—that is essential for the brain's capacity to learn from experience 8 .
While the Milan conference focused on molecular chemistry, the concept of brain development is also illuminated by famous behavioral experiments. One of the most captivating is the Stanford Marshmallow Experiment, led by Walter Mischel in the early 1970s 5 . This experiment offers a window into how the developing brain's chemistry and circuitry manage the critical skill of delayed gratification.
A child was led into a quiet room where a single treat, such as a marshmallow or pretzel stick, was placed on a table. The researcher made a simple offer: the child could eat the one treat now, or, if they waited for 15 minutes, they would get a second treat. The researcher then left the room, and the child's struggle with temptation began 5 .
Mischel and his team observed fascinating spontaneous strategies the children used to control their impulses:
"not thinking about a reward enhances the ability to delay gratification, rather than focusing attention on the future reward" 5
This behavioral finding has a chemical counterpart. The ability to exert self-control is heavily influenced by the prefrontal cortex and its neurochemical pathways. The children were, in effect, developing cognitive strategies to manage their emotional and chemical impulses, a key skill in the maturing brain's toolkit.
| Experiment | Number of Children | Age Range |
|---|---|---|
| Original 1970 Study | 32 (16 boys, 16 girls) | 3 yrs 6 mo - 5 yrs 8 mo |
| 1972 Study (Exp. 1) | 50 (25 boys, 25 girls) | 3 yrs 6 mo - 5 yrs 6 mo |
| 1972 Study (Exp. 2) | 32 | 3 yrs 9 mo - 5 yrs 3 mo |
| 1972 Study (Exp. 3) | 16 (11 boys, 5 girls) | 3 yrs 5 mo - 5 yrs 6 mo |
| Strategy Category | Specific Behaviors Observed |
|---|---|
| Physical Avoidance | Covering eyes, turning away from the treat |
| Self-Distraction | Inventing games, singing, talking to themselves |
| Cognitive Re-framing | Thinking about the treat as a picture or a cloud |
| Self-Soothing | Trying to fall asleep, sitting on their hands |
The journey to understand the brain's chemistry relies on a sophisticated toolkit. From the fundamental tools of the 1970s to modern imaging, these reagents and technologies allow scientists to see the unseeable.
| Tool or Reagent | Primary Function in Research |
|---|---|
| Molecular Imaging (PET, fMRI) | Allows scientists to visualize metabolic activity and brain structure in living subjects, tracing the pathways of chemical compounds 6 . |
| Electroencephalogram (EEG) | Records the brain's electrical activity from the outside, helping researchers understand brain functioning in very young children 8 . |
| Radioactive Tracers | Used in Positron Emission Tomography (PET), these injected substances allow for the tracking of molecular mechanisms in the brain 6 8 . |
| Synaptic Receptor Assays | Chemical methods to study the density and function of synapses and neuroreceptors, crucial for understanding communication between brain cells 1 . |
The questions posed at the 1970 Milan conference are more relevant than ever. The foundational idea that brain development must be studied through an integrated, multidisciplinary lens has been fully vindicated. Today's neuroscience continues to explore the delicate balance between the enduring significance of early brain development and its impressive lifelong capacity for growth and change, or plasticity 8 .
We now know that while the brain undergoes its most dramatic development during the first few years of life, the processes of fine-tuning synapses and strengthening neural circuits continue well into adolescence 8 .
The chemistry of our brains is not a static script but a dynamic, lifelong conversation between our biology and our experiences. From the pioneering work of the past to the cutting-edge research of today, the quest to understand the chemical masterpiece of our brain continues to be one of humanity's most exciting and meaningful journeys.