Summary: The tiny zebra finch is a vocal-learning specialist, but its most surprising ability lies deep in its brain. Researchers have found that newly born neurons in these birds do not carefully weave around existing tissue. Instead, they tunnel directly through mature brain matter, displacing established cells as they migrate to their targets.
This aggressive mode of movement may help explain why humans largely stop producing new neurons after birth: limiting adult neurogenesis could protect long-term memories and stable networks from being disturbed by migrating cells.
Key Findings
- Evolutionary trade-off: The study suggests humans may have sacrificed widespread adult neurogenesis to preserve the integrity of existing memories and circuits.
- Metastatic parallel: The observed “tunneling” behavior resembles the invasive movement of some metastatic cancer cells, indicating possible shared mechanisms of cellular motility.
- Therapeutic potential: Because these neurons do not rely on glial scaffolds to migrate, the results open possibilities for stem-cell therapies that could stimulate neurogenesis without first rebuilding supporting structures.
- Repair versus retention: Regular neuronal replacement in the finch brain supports learning and recovery from injury, but raises questions about how much preexisting information may be altered or lost when new neurons displace established tissue.
Source: Boston University
Despite its small size—small enough to fit in the palm of a hand—the zebra finch is a remarkable learner. Native to Australia, this songbird is well known for acquiring and refining new songs, which has made it a valuable model for studying how brains encode vocal learning and other acquired skills.
Researchers at Boston University applied high-resolution imaging to the finch brain and reported a striking behavior of migrating neurons: rather than moving around mature structures, the new cells often carved tunnels through existing tissue, deforming and displacing mature somas, dendrites, and neuropil as they progressed.
Using electron microscopy–based connectomics to map the cellular environment at very high resolution, the team observed migrating neurons contacting and physically reshaping surrounding circuit elements. The deformations frequently appeared as tunnel-like paths where migrating cells displaced mature structures to reach their destinations in the adult striatum.
Benjamin Scott, assistant professor of psychological and brain sciences at Boston University and the study’s corresponding author, describes the behavior as new neurons “forging a path through a dense jungle.” While this movement likely supports learning and repair, it might come at the cost of disrupting existing cells and stored information. That trade-off could be a reason why extensive adult neurogenesis is restricted in humans and many other mammals.
Scott and colleagues propose two ways to interpret the findings. One view is protective: by limiting adult neurogenesis, humans reduce the risk that migrating neurons will damage long-term memories or stable circuits. An alternative, more optimistic view is that the finch example shows migrating neurons can traverse tissue without glial scaffolds—structures commonly thought to be required for directed migration. Because most glial scaffolds decline after human birth, this discovery suggests that inducing neurogenesis in adults might not require restoring those scaffolds first.
This observation has practical implications: if researchers can identify the genes and signals that enable neurons to tunnel through mature tissue, they may be able to design stem-cell therapies or other interventions that promote brain repair without extensive scaffold reconstruction.
Next steps
Scott’s laboratory is now investigating the molecular biology that drives this behavior. They are using single-cell RNA sequencing to profile migrating neurons and identify the genes and signaling partners involved in their migration, interaction with mature cells, and eventual integration into circuits. These experiments aim to reveal how migrating neurons communicate with surrounding cells, how they choose where to stop, and whether they signal in advance to mitigate damage.
Studying songbirds, Scott notes, offers a window into conserved biological mechanisms. While the phrase “bird brain” is often used as an insult, detailed study of songbird neurobiology may reveal principles useful for understanding and potentially treating human brain disorders.
Publication and funding
The findings appear in Current Biology. This research was supported by the BU Neurophotonics Center and included collaborators from the MRC Laboratory of Molecular Biology and the Max Planck Institute for Biological Intelligence.
Key Questions Answered:
A: It’s a trade-off. In species like birds, ongoing neurogenesis supports learning and recovery from injury. In humans, long-term stability of memories and complex learned behaviors may be prioritized, so extensive adult neurogenesis could pose risks to those durable networks.
A: That is an active area of research. The discovery that neurons can move without glial scaffolds shifts the focus to identifying molecular triggers for migration. If scientists can control those mechanisms, it may be possible to promote repair while minimizing disruption to existing circuits.
A: In terms of regeneration, yes. Birds, reptiles, and fish continue to generate neurons throughout life, allowing more frequent circuit renewal. Humans generally retain most of the neurons they are born with, prioritizing long-term circuit stability.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- The journal paper was reviewed in full.
- Additional context was added by staff.
About this neurogenesis research news
Author: Jennifer Rosenberg
Source: Boston University
Contact: Jennifer Rosenberg – Boston University
Image credit: Neuroscience News
Original research: Open access. “Songbird connectome reveals tunneling of migratory neurons in the adult striatum” by Naomi R. Shvedov, Simon J. Castonguay, Alexandra Rother, Delta E. Schick, Joergen Kornfeld, and Benjamin B. Scott. Published in Current Biology. DOI: 10.1016/j.cub.2026.03.057
Abstract
Songbird connectome reveals tunneling of migratory neurons in the adult striatum
Immature neurons in the adult brain migrate into existing circuits, contributing to plasticity, learning, and complex behaviors. While prior work has explored molecular mechanisms and functional outcomes of adult neurogenesis, few studies have examined the physical interactions between migrating neurons and their mature microenvironment.
Using electron microscopy–based connectomics, the authors examined how migrating neurons interact with mature circuit elements in the adult zebra finch striatum. Migratory neurons contacted a range of structures, including axons, dendrites, synapses, and somas of mature neurons. These interactions were often structurally complex and frequently involved pronounced deformation of mature somas and surrounding neuropil.
Those deformations appeared as tunnel-like paths created by migrating neurons as they displaced mature structures along their trajectories. Together, the findings suggest that migrating neurons can physically reshape mature circuits to reach their targets, revealing an unexpected degree of structural and functional plasticity in the adult brain.