# Mapping in unprecedented detail human mini-brains’ response to chemical signals
**Source**: https://bsse.ethz.ch/news-and-events/d-bsse-news/2026/02/mapping-in-unprecedented-detail-human-mini-brains-response-to-chemical-signals.html
**Parent**: https://bsse.ethz.ch/news-and-events.html
Scientists from the Quantitative Developmental Biology lab of Barbara Treutlein and their colleagues from the Universities of Basel and Copenhagen have created the most detailed picture yet of how early human brain tissue responds to the chemical signals that guide brain development, offering a powerful new resource for studying the origins of the human nervous system – and what happens when development goes off course.
In a study published in *Nature Methods*, the researchers used lab-grown “mini-brains,” known as neural organoids, to systematically test how different chemical cues shape early brain organisation. Their findings show that small changes in when, how much, and which signals are applied can dramatically alter how these tissues develop.
**The role of morphogens in early brain patterning**
During early development in the foetus, the growing brain is guided by chemical messengers called morphogens. These signals act like instructions, telling cells where they are and what they should become, such as tissue destined for the forebrain, midbrain, or spinal cord. Understanding how human cells respond to these cues has been difficult, largely because scientists cannot directly study early human brain development *in vivo*.
Neural organoids, grown from human stem cells, have become an important workaround since they serve as valuable human model systems in neuroscience and allow studying neural regionalisation during development: these tiny, three-dimensional tissues mimic some features of the developing brain. But until now, researchers lacked a broad, systematic view of how organoids respond to different morphogen signals.
**A systematic screen of timing, dose, and signal combinations**
To tackle this, the research team exposed organoids to a wide range of morphogen conditions. They varied the timing, concentration, and combinations of signals, and then closely examined how individual cells responded using a method called single-cell transcriptomic screens. This allowed them to see, cell by cell, how different “recipes” changed the makeup and identity of the developing tissue.
> “Turned out, that timing and dosages of morphogen treatment has an enormous impact on organoid cell type composition. Mapping those sensitive windows helps us better control how brain organoids develop and will improve *in vitro* models.”
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> Nadezhda Azbukina, first co-author of this study and doctoral candidate in the Quantitative Developmental Biology lab of Barbara Treutlein
The results reveal that brain development is highly sensitive to its chemical environment. Even when using the same signals, changing the dose or applying them earlier or later led to strikingly different outcomes. Beyond creating a detailed map of how neural organoids respond to developmental cues, the scientists are working on a prediction tool to forecast how a particular stem cell culture will develop before an experiment even begins. The insights gained from combining these large single-cell transcriptomic datasets with machine-learning tools, have wide-reaching implications for improving models of brain development and neurological disorders.
## Find original publication in *Nature Methods*:
Sanchís-Calleja, F., Azbukina, N., Jain, A. et al. (2025) [external page Systematic scRNA-seq screens profile neural organoid response to morphogens](https://rdcu.be/e2hM2). *Nature Methods*. https://doi.org/10.1038/s41592-025-02927-5
## Find feature in *Nature Methods – Research Briefing*:
[external page Dissecting how morphogens shape cell fates in human neural organoids.](https://rdcu.be/e2huf) *Nature Methods* (2025). https://doi.org/10.1038/s41592-025-02959-x
Learn about research in the [Quantitative Developmental Biology lab led by Barbara Treutlein](https://bsse.ethz.ch/qdb)