Our Brains May Have Pre-Configured Instructions to Understand the World When We’re Born
When do our first thoughts develop? Do they spark in infancy, somewhere in the womb, or even earlier, back when the brain is only a budding clump of cells? Scientists and philosophers have been wrestling with this for decades, trying to figure out whether thinking is wired into our genes from the start or shaped entirely by experience.
A new study in Nature Neuroscience offers an intriguing clue. Using lab-grown brain organoids, scientists from the University of California, Santa Cruz, along with collaborators in Germany and Switzerland, found that neurons begin firing in recognizable, information-like patterns long before any sensory system is active. In other words, the brain might be preloaded with a kind of internal template for reading the world, even before the world reaches us.
These findings deepen our understanding of how the brain forms and could help researchers study neurodevelopmental disorders or how toxins influence fetal development.
Read More: When It Comes to Thinking, Our Brains Are Surprisingly Slow
3D Brain Organoids Can Mimic How Brains Operate
Because the early brain is tucked inside the womb, observing its first electrical signals has always been a challenge. Neurons fire to transmit information — like the operating system of a computer — but pinpointing when that system switches on is practically impossible in a human embryo. So the team turned to brain organoids, 3D clusters of neural tissue grown from human and mouse stem cells.
Organoids aren’t perfect replicas of a brain, but they offer something simple cultures can’t: a more realistic arrangement of cell types and structures. They also develop without sensory exposure, making them ideal for testing whether early firing patterns are genetically programmed rather than learned.
“We grow brain organoids to peer into this primordial version of the brain’s operating system and study how the brain builds itself before it’s shaped by sensory experience,” said the study’s senior author, Tal Sharf, assistant professor of biomolecular engineering at the Baskin School of Engineering, in a press release.
To track the organoids’ electrical signals, the researchers used custom microchips. Their goal was to observe when organized activity appears and whether it depends on the brain receiving information from the outside world.
Processing Information Without Any Input
As the organoids assembled from stem cells into early neural tissue, the microchips began picking up structured electrical signals. Within the first months of development, which is long before a real fetus can see or hear, the neurons were already generating patterns associated with processing sensory information.
To locate electrical activity of single neurons in organoids, researchers used this CMOS-based microelectrode array chip.
(Image Credit: Carolyn Lagattuta/ UC Santa Cruz/ CC BY-SA)
“These cells are clearly interacting with each other and forming circuits that self-assemble before we can experience anything from the outside world,” Sharf said.
Scientists have long known that the brain has a “default mode” of activity, a baseline firing pattern that becomes more specialized after sensory input arrives. Surprisingly, the organoids showed patterns closely resembling that default mode, even in individual neurons.
Without ever encountering light, sound, or touch, these tiny clumps of tissue were already producing time-based firing sequences that looked ready to be shaped into sensory pathways. It suggests that the developing brain starts with an internal blueprint rather than a blank slate.
Treating Neurodevelopmental Disorders as Early as Possible
The findings indicate that these early firing sequences aren’t built purely through experience but are constrained by a preconfigured architecture set during development. Evolution may have equipped the nervous system with a starter map that prepares it to handle the world from the moment senses switch on.
This could transform how scientists study neurodevelopmental disorders. If the earliest wiring already sets the stage for later brain function, disruptions — genetic or environmental — may leave detectable patterns far earlier than previously believed.
“That would allow us to develop therapies, working with clinicians at the preclinical level to potentially develop compounds, drug therapies, and gene editing tools that could be cheaper, more efficient, higher throughput,” Sharf said.
Ultimately, the research suggests that our capacity to process information begins astonishingly early. Long before our first experiences, neurons are already rehearsing the rhythms that will one day let us interpret the world.
Read More: How Does the Brain Turn an Internal Need into a Focused Craving?
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