Our Brains May Have Pre-Configured Instructions to Understand the World When We’re Born

When are our first thoughts born? Do they appear in infancy, somewhere in the womb, or even earlier, when the brain is just a budding mass of cells? Scientists and philosophers have been pondering this question for decades, trying to determine whether thinking is hardwired into our genes from the start or whether it is shaped entirely by experience.

A new study in Natural neuroscience offers an intriguing clue. Using lab-grown brain organoids, scientists at the University of California, Santa Cruz, along with German and Swiss collaborators, found that neurons begin firing in recognizable, information-like patterns long before a sensory system is active. In other words, the brain might be preloaded with some 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.

Learn more: When it comes to thinking, our brains are surprisingly slow

3D brain organoids can mimic how the brain works

Because the early brain is nestled inside the uterus, observing its first electrical signals has always been a challenge. Neurons fire to transmit information – like a computer’s operating system – but it is virtually impossible to determine when this system activates in a human embryo. So the team turned to brain organoids, 3D clumps of neural tissue grown from human and mouse stem cells.

Organoids are not perfect replicas of a brain, but they offer something that simple cultures cannot: 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 are growing brain organoids to examine this primordial version of the brain’s operating system and study how the brain is constructed before being shaped by sensory experience,” said the study’s lead author, Tal Sharf, assistant professor of biomolecular engineering in 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 organoids assembled from stem cells to form early neural tissue, microchips began to sense structured electrical signals. During the first months of development, long before a real fetus can see or hear, neurons were already generating patterns associated with processing sensory information.

“These cells clearly interact with each other and form 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 basic firing pattern that becomes more specialized after sensory information arrives. Surprisingly, the organoids showed patterns closely resembling this default mode, even in individual neurons.

Without ever encountering light, sound, or touch, these tiny clumps of tissue were already producing temporal firing sequences that seemed ready to be transformed into sensory pathways. This suggests that the developing brain starts with an internal blueprint rather than a blank slate.

Treat neurodevelopmental disorders as early as possible

The results indicate that these first firing sequences are not constructed solely by experience, but are constrained by a preconfigured architecture defined during development. Evolution may have equipped the nervous system with a jumpstarter that prepares it to handle the world from the moment the senses become activated.

This could transform the way scientists study neurodevelopmental disorders. If early wiring already sets the stage for later brain function, disruptions – genetic or environmental – can leave detectable patterns much earlier than previously thought.

“This 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 effective and higher throughput,” Sharf said.

Ultimately, research suggests that our ability to process information begins surprisingly early. Long before our first experiences, neurons are already repeating the rhythms that will one day allow us to interpret the world.

Learn more: How does the brain transform an internal need into a targeted desire?

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