---
title: A Fruit Fly Atlas Maps How a Newborn Neuron Settles Which Type It Becomes
description: A Stowers Institute atlas of 232,251 fruit fly cells maps how a neuron settles its type in its first hours, and why brain-repair therapy is decades off.
author: Darie Nani (Editor-in-Chief)
updated: 2026-09-15T19:21:43.294Z
canonical: https://www.sovereignmagazine.com/article/fruit-fly-brain-atlas-neuron-identity
image: https://cdn.nanimediahouse.com/pexels-two-scientists-working-in-a-well-equipped-laboratory-with-mi-4031420.jpg
categories: Science & Tech
content_type: News
region: Global
publication: Sovereign Magazine
schema_type: Article
---

A brain runs on hundreds, sometimes thousands, of kinds of neurons, and all of them trace back to one small pool of stem cells. How a single newborn cell settles which kind it will become is one of the older open questions in developmental biology, and a new study lays out the most detailed map yet of the moment it happens.

The map comes from the lab of Neşet Özel, PhD, at the Stowers Institute for Medical Research in Kansas City, Missouri, and was [published in the Proceedings of the National Academy of Sciences](https://pmc.ncbi.nlm.nih.gov/articles/PMC13505965/) on August 19, 2026. Özel's team tracked 232,251 individual cells across the development of the fruit fly visual system, covering more than 250 distinct cell types. For each cell they recorded two things at once, which genes it was expressing and which regulatory stretches of its DNA, the switches that turn genes on and off, were open. Özel calls the result “simply a map” of what each neuron expresses and which genomic switches controlling that expression are accessible.

In their account, a neuron's lasting identity is not simply copied from its parent stem cell. It is established during a brief critical period right after the cell is born, when the regulatory landscape of its DNA is heavily rearranged. Many of the enhancers tied to a neuron's identity were completely shut in the parent stem cell and opened only after the cell finished its final division.

“The DNA landscape is dramatically remodeled in the first hours of a neuron's life,” Özel said. “Identity isn't simply copied from the stem cell. In an important sense, it is computed during a specific critical period.” He calls this the most striking finding of the paper.

A transcription factor active before the division could work through an entirely different set of DNA switches afterward, so that the same protein “would be doing something else entirely in the progenitor.” Özel notes that this is “not really clear in the field” and “not widely appreciated.”

## Almost Every Neuron Type Wired Itself Differently

“We expected to find more consistency in terms of which factors control which genes across the brain,” said first author McKenzie Treese, a Computational Biology Scholar in the lab. “Instead, almost every neuron type had its own wiring.” The same transcription factor could regulate different genes in different neuron types, and the same gene could answer to different transcription factors through different enhancers depending on the cell it sat in.

“The regulation is deeply context dependent,” Özel said. “Each neuron type uses its own combination of regulators. That flexibility gives the nervous system a way to generate enormous cellular diversity from a limited genetic toolkit.” The set of switches open in any one cell turned out to be so specific that the researchers describe it as working almost like a fingerprint of that neuron's identity.

The fly study is one of a wave of large single-cell and multi-omic maps of developing brains across species, including the FlyWire fruit-fly connectome and multiomic atlases of the human cortex. A fruit fly's brain holds on the order of a hundred thousand neurons, a human brain holds roughly 86 billion, and the jump from fly to mouse is already large.

## Replacing Lost Neurons Means Making the Exact Right Type

Parkinson's disease, ALS, and glaucoma each destroy specific cell types, and replacing them means making the right neuron, not just any neuron.

“Medicine needs to make specific types of neurons to treat various diseases, and to make a specific type of neuron, you need to know that neuron's recipe,” Özel said. “That recipe, as it turns out, is not that easy to come up with.”

“Before therapy, we need to understand the fundamentals,” Özel said. “That requires decades of research and building up principles.” Cell-replacement therapy is not waiting on this study to get moving: dopamine-neuron replacement for Parkinson's is already in [late-stage human testing](https://www.bluerocktx.com/first-parkinsons-disease-patient-treated-in-bluerocks-pivotal-phase-iii-trial-of-investigational-cell-therapy-bemdaneprocel/), using today's differentiation methods that rely on known transcription factors and signals rather than anything in the fly atlas. The atlas is groundwork for the harder cases, where the recipe is still unknown.

The work was funded by the National Institute of Neurological Disorders and Stroke and the National Eye Institute, both part of the National Institutes of Health, and by the Esther A. and Joseph Klingenstein Fund. Claude Desplan, PhD, is a co-author.

## FAQ

**Q: How does a neuron decide what type to become?**
In this study, the decisive step is not inherited whole from the parent stem cell. Özel's team places it in a short window right after a neuron is born, when specific DNA switches open for the first time and lock in which genes that cell will run. Many of those switches were closed in the stem cell and opened only after the neuron's final division.

**Q: What is a single-cell brain atlas?**
It is a catalog that records the molecular state of individual cells rather than an averaged readout of tissue. This one logged 232,251 cells of the fruit fly visual system and, for each, captured both its active genes and its open regulatory DNA, sorting them into more than 250 cell types.

**Q: What are DNA switches, or enhancers?**
Enhancers are stretches of regulatory DNA that control when and where a gene turns on. A cell can express the same gene through different switches, and the study found that which switches are open in a given neuron is specific enough to act almost like a fingerprint of its identity.

**Q: Does this bring us closer to treating Parkinson's or ALS?**
Not directly or soon. Replacing lost neurons requires making the exact right cell type, and the atlas is a step toward reading those recipes, but Özel frames useful therapy as decades of further research away. Parkinson's cell-replacement trials already underway rely on existing methods, not on this fly study.