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Scientific Frontline: "At a Glance" Summary
- Main Discovery: Neurons positioned in the wrong location, known as heterotopias, can successfully integrate into brain circuits and take over the functional role of the normal cerebral cortex, defying the assumption that precise anatomical placement is required for function.
- Methodology: Researchers utilized a mouse model with induced heterotopias and performed functional mapping during a sensory task requiring the distinction of whiskers; they employed targeted deactivation to isolate the contributions of normal versus misplaced neurons.
- Key Data: Mice continued to perform sensory tasks normally when the healthy cortex was deactivated; however, the specific inhibition of the misplaced neuronal clusters resulted in immediate and complete failure of the task.
- Significance: This study fundamentally alters the understanding of brain plasticity, demonstrating that cellular identity and connectivity can override spatial positioning to maintain neurological function.
- Future Application: These findings validate the potential of regenerative therapies, such as neuronal grafts and brain organoids, suggesting they can be effective treatments without needing to perfectly replicate natural brain architecture.
- Branch of Science: Neuroscience (Neurodevelopment and Plasticity).
- Additional Detail: Analysis revealed that these stray neurons formed neural circuits almost identical to those in the healthy cortex, establishing correct connections with both the rest of the brain and the spinal cord.
A team from UNIGE has shown that neurons positioned in the wrong place can still perform their function without disrupting the brain’s overall operation.
Can the brain keep working when its architecture changes? Researchers at the University of Geneva have discovered that neurons located in the wrong place can still carry out their normal function — challenging long-held assumptions about how the brain is organized. Published in Nature Neuroscience, this study reveals an unexpected ability of the brain to adapt.
Neurons are specialized cells responsible for transmitting and processing information through electrical and chemical signals. They form the basic units of the brain and nervous system function. Until now, scientists believed that neurons had to be in the correct location for the brain to function properly. But a recent study by UNIGE researchers shows that neurons positioned incorrectly can not only survive, but also completely take over the role of the normal cerebral cortex.
To reach this conclusion, the team studied mice with “heterotopias” — malformations where neurons end up in the wrong location, forming clusters beneath the cortex. This phenomenon also occurs in humans and, in severe cases, can lead to epilepsy and intellectual disabilities. Observing these mice, the researchers made a surprising discovery: these misplaced neurons form circuits almost identical to those of the normal cortex, with similar connections to the rest of the brain and spinal cord.
It’s like moving an entire neighborhood to a different part of a city, and the residents still maintain the same relationships.
Neurons That Step in When Needed
Even more striking, when scientists temporarily deactivated the normal cortex during a delicate sensory task—distinguishing between two whiskers—the mice continued to perform normally. The misplaced neurons had taken over. Conversely, inhibiting these neurons caused the task to fail completely, proving they had become essential for sensory processing.
“It’s like moving an entire neighborhood to a different part of a city, and the residents still maintain the same relationships and connections with the rest of the city,” explains Sergi Roig-Puiggros, postdoctoral researcher at UNIGE’s Department of Basic Neurosciences and first author of the study.
Implications for Medicine and Evolution
The findings shed light on evolutionary mechanisms that allow new brain structures to emerge. They also open promising avenues for regenerative medicine: “If neurons can function normally in an abnormal architectural context, then neuronal grafts or brain organoids might not need to perfectly replicate natural brain structure to be effective,” notes Denis Jabaudon, professor and head of UNIGE’s Department of Basic Neurosciences, who led the study.
The next step for the research team is to determine whether this preserved function of misplaced neurons occurs only in heterotopias or also in other neurodevelopmental disorders.
Reference Material: What Is: Organoid | What Is: Biological Plasticity
Published in journal: Nature Neuroscience
Title: Position-independent emergence of neocortical neuron molecular identity, connectivity and function
Authors: Sergi Roig-Puiggros, Maëlle Guyoton, Dmitrii Suchkov, Aurélien Fortoul, Giulio Matteucci, Sabine Fièvre, Alessandra Panzeri, Nikolaos Molochidis, Francesca Barcellini, Emma Maino, Charlie G. Foucher, Daniel Fuciec, Awais Javed, Esther Klingler, Fiona Francis, Valerio Zerbi, Camilla Bellone, Marat Minlebaev, Sami El-Boustani, Françoise Watrin, Jean-Bernard Manent, and Denis Jabaudon
Source/Credit: Université de Genève
Reference Number: ns011626_01
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