Your brain begins as a single cell. When all is said and done, it will house an incredibly complex and powerful network of some 170 billion cells. How does it organize itself along the way? Cold Spring Harbor Laboratory neuroscientists have\u00a0come up with\u00a0a surprisingly simple answer that could have\u00a0far-reaching\u00a0implications for\u00a0biology and artificial intelligence.\u00a0<\/p>\n
Stan\u00a0Kerstjens, a postdoc in\u00a0Professor\u00a0Anthony Zador’s lab, frames the question in terms of\u00a0positional information.\u00a0“The only thing a cell\u00a0‘sees’\u00a0is itself and its neighbors,”\u00a0he\u00a0explains.\u00a0“But its fate depends on where it sits. A cell in the wrong place becomes the wrong thing, and the\u00a0brain\u00a0doesn’t\u00a0develop right. So, every cell must solve two questions: Where am I? And who do I need to become?”\u00a0<\/p>\n
In\u00a0a\u00a0study\u00a0published in\u00a0Neuron,\u00a0Kerstjens, Zador, and colleagues\u00a0at Harvard\u00a0University\u00a0and\u00a0ETH\u00a0Z\u00fcrich\u00a0put\u00a0forward a\u00a0new theory for\u00a0how the brain organizes itself during development.\u00a0<\/p>\n
For a long time, researchers thought that\u00a0cells exchanged\u00a0positional\u00a0information\u00a0mainly\u00a0through\u00a0chemical signaling.\u00a0This\u00a0works well\u00a0when dealing with just a few\u00a0cells,\u00a0Kerstjens\u00a0explains.\u00a0But the brain\u00a0isn’t\u00a0a few cells.\u00a0It’s\u00a0billions of neurons, each needing to land in exactly the right place. Chemical signals can only travel so far before fading. So, how do cells deep in a growing brain automatically ‘know’ where they are?\u00a0<\/p>\n
The answer,\u00a0Kerstjens\u00a0proposes, hits\u00a0close to home.\u00a0“Consider how human populations spread across a country over generations,” he\u00a0says. “Descendants settle near their parents, so people who share ancestry end up in neighboring regions, producing large-scale geographic structures\u00a0without long-range communication.\u00a0We argue that a similar principle\u00a0operates\u00a0in\u00a0the developing brain.\u00a0Cells that descend from the same progenitor tend to remain near one another.”\u00a0<\/p>\n
To test this theory,\u00a0Kerstjens\u00a0and colleagues built what they call a “lineage-based model of scalable positional information.” They started with theoretical computations. Then they tested their hypothesis\u00a0at scale\u00a0by looking at\u00a0individual and group gene expression in developing mouse brains. Finally, they confirmed their\u00a0results in zebrafish, showing that the model can\u00a0be\u00a0used across brains of\u00a0different sizes.\u00a0<\/p>\n
Kerstjens\u00a0says the model supports the notion that chemical signaling\u00a0works in conjunction with a lineage-based mechanism to convey positional\u00a0information.\u00a0And while his work focuses on\u00a0the\u00a0brain,\u00a0the theory could\u00a0apply to many\u00a0other\u00a0types of developing\u00a0tissue, including\u00a0tumors.\u00a0There may even be implications for\u00a0self-replicating AI models that\u00a0pass\u00a0information from one generation to the next, just as our own brain cells do.\u00a0<\/p>\n
Perhaps most\u00a0importantly,\u00a0showing\u00a0how a single cell grows into a complex\u00a0organ could help scientists\u00a0solve\u00a0fundamental mysteries of the\u00a0mind.\u00a0<\/p>\n
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The brain\u00a0somehow\u00a0makes us intelligent. How did it manage to accumulate this\u00a0capability, not just over its\u00a0developmental time, but over\u00a0evolutionary time?\u00a0This\u00a0is one piece in that big puzzle.”\u00a0<\/p>\n
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Stan\u00a0Kerstjens, postdoc in\u00a0Professor\u00a0Anthony Zador’s lab<\/p>\n
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Source:<\/p>\n
Cold Spring Harbor Laboratory<\/a><\/p>\n Journal reference:<\/p>\n