A collaborative team including the University of California, Santa Cruz, Johns Hopkins University, and several institutions in Germany and Switzerland has used organoids—miniature human brain tissue models—to reveal the brain's innate, pre-programmed "operating system." Published in *Nature Neuroscience*, the latest research overturns conventional wisdom, showing that the earliest neuronal firing in the brain occurs in a structured pattern, completely independent of any external experience. This discovery suggests that the brain pre-programs basic "instructions" on how to interact with the world before a person is born.
Humans have long pondered: when exactly does thought begin to form? Is the brain pre-configured, or do thought patterns gradually develop through sensory experiences of the surrounding world? The brain functions similarly to a computer, relying on the electrical signals of neurons to transmit information. However, the exact timing of these signals has been difficult to study because the developing human brain is protected within the womb and cannot be directly observed.
In this study, the team guided stem cells to develop into brain tissue and then used a specialized array of microelectrodes, similar to computer chips, to record their electrical activity. Observing the brain tissue's self-assembly from stem cells into complex structures capable of processing sensory information and ultimately generating language and conscious thought, they discovered that in the first few months of development, long before the human brain can receive and process complex external sensory information such as vision and hearing, its internal cells begin to spontaneously emit electrical signals with specific patterns. The patterns of these signals are strikingly similar to the characteristic patterns exhibited when processing sensory information.
When observing the firing activity of individual neurons in organoids, the team discovered that even without receiving any sensory input from the external world, the neural networks could spontaneously generate complex and time-series-characteristic firing activities. This strongly suggests the existence of an inherent, genetically encoded developmental blueprint in the neural structure of the living brain.
Understanding the fundamental neural structures that enable organoids to spontaneously produce living human brains opens up numerous possibilities for a better understanding of human neurodevelopment, neurological diseases, and the effects of environmental toxins on the brain. These models possess the fundamental ability to capture complex neural dynamics that are likely closely related to certain pathogenesis mechanisms. In the future, the team will explore the development of new compounds, drug therapies, or gene-editing tools at the preclinical level.
[Editor's Note]
Even when seeds are still deeply buried in the soil, they possess the "potential" to sprout. This isn't something the seed "learns" later in life; it's a fundamental program written into their genes during the evolution of life. Similarly, in the early stages of human brain development, neurons can spontaneously emit complex electrical signals, engaging in preliminary interactions with the world and preparing for processing more complex external sensory signals later on. This is also determined by the fundamental coding of human genes. In other words, a newborn baby's brain is not a blank slate, but rather carries the "factory settings" pre-programmed by genes. This discovery helps scientists better understand the mechanisms of human brain development and may provide inspiration for treating congenital neurological diseases using techniques such as gene editing.
(Original title: Unraveling the mystery of when thought begins to form: Organoid research reveals the brain's innate "operating system")
