Summary: The tiny zebra finch is a champion of vocal learning, but its most surprising skill lies deep inside its brain. Researchers have found that when these birds grow new neurons, the young cells do not gently weave around established structures. Instead, they tunnel directly through mature tissue, displacing existing cells as they migrate. This aggressive migration may help explain why humans largely stop producing new neurons after birth—to protect long-term memories and stable circuits from being disturbed.
Using high-resolution imaging, researchers at Boston University tracked how newborn neurons in the zebra finch navigate the adult brain. The observations reveal a mode of neurogenesis that physically alters surrounding tissue, raising questions about trade-offs between plasticity, repair, and memory preservation across species.
Key Findings
- Evolutionary trade-off: The study suggests that humans may have evolved limited adult neurogenesis to preserve established neural circuits and long-term memories, trading continuous renewal for stability.
- Parallel to cancer cell behavior: The researchers noted similarities between the neurons’ tunneling movement and the invasive behavior seen in certain metastatic cancer cells, pointing to shared mechanisms of aggressive cell migration.
- Stem-cell implications: Because these neurons migrate without relying on glial scaffolds, future regenerative therapies might not need to recreate those scaffolds before promoting neuron replacement.
- Repair versus retention: Zebra finch brains appear to undergo continual renewal, which supports repair and learning but may also displace older structures and potentially affect stored information.
Source: Boston University
Despite its small size—small enough to sit in your palm—the zebra finch is a powerful learner. Native to Australia, this songbird is widely used in research on vocal learning and the neural basis of acquiring new sounds. The species’ robust adult neurogenesis made it an ideal model for studying how new neurons integrate into existing adult circuits.
The team used electron microscopy–based connectomics, a powerful imaging approach that produces ultrahigh-resolution volumes of brain tissue. That level of detail allowed them to observe how migrating immature neurons interact with synapses, axons, dendrites, and the somas of mature cells in the adult striatum.
Rather than delicately avoiding established elements, the migrating neurons frequently deformed and displaced mature structures, creating tunnel-like paths through the neuropil. These physical deformations show that adult-born neurons can actively reshape the circuits they enter, rather than merely fitting into predefined spaces.
The study’s lead author, Benjamin Scott, an assistant professor of psychological and brain sciences at Boston University, describes the behavior as new neurons acting like “explorers forging a path through a dense jungle.” That exploratory mode may be an efficient strategy for integrating new cells and restoring damaged networks, but it likely comes at the cost of altering or removing existing cellular arrangements.
Scott and colleagues propose two interpretations of these observations. One is a protective hypothesis for human evolution: by limiting adult neurogenesis, mammals may reduce the risk that newly generated, forceful migratory neurons will disrupt long-lived memory circuits. The second, more optimistic perspective is that neurons can migrate without glial scaffolding, which means that promoting neurogenesis for therapeutic repair might be more feasible than previously thought.
Many mammals lose the glial scaffolds that aid neuron migration after birth, a factor often considered an obstacle to adult brain regeneration. The zebra finch results suggest that neurons can use alternative strategies to move through dense tissue, implying that engineered or stem-cell–based repairs might not require reconstructing specialized glial highways first.
Next steps
Scott’s laboratory is now exploring the molecular drivers of this migratory behavior. Using single-cell RNA sequencing, the researchers are identifying genes and signaling pathways that guide migrating neurons, that mediate their interactions with surrounding cells, and that signal when and where they should stop and integrate into circuits.
Answering these questions will clarify whether migrating neurons actively communicate with resident cells to minimize damage, or whether they simply displace structures as a consequence of their mode of movement. Understanding the molecular cues could provide targets for therapies that encourage beneficial regeneration while limiting disruption of existing networks.
“We share much of our basic brain biology with other vertebrates,” Scott notes. “By studying songbirds, we can reveal mechanisms of plasticity and repair that may inform how to protect or restore human brains.”
Funding: This research received support from the BU Neurophotonics Center and included collaborators from the MRC Laboratory of Molecular Biology (UK) and the Max Planck Institute for Biological Intelligence (Germany).
Key Questions Answered:
A: It’s a balance. In birds, ongoing neurogenesis supports learning and recovery from injury. In humans, where long-term, complex memories are crucial, frequent structural disruption by migrating neurons could be detrimental. Evolution may have favored stability over continual renewal in our lineage.
A: That is a major research goal. The new finding that neurons can migrate without glial scaffolds shifts how scientists think about stimulating adult neurogenesis. Identifying the genes and signals that enable this tunneling behavior will be essential before safe, targeted therapies can be developed.
A: In terms of adult regeneration, yes—many birds, fish, and reptiles continually add new neurons and renew brain circuits. Humans, by contrast, retain most neurons formed before birth and rely on mechanisms that preserve circuit stability throughout life.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- The journal paper was reviewed in full.
- Additional context was added by our staff.
About this neurogenesis research news
Author: Jennifer Rosenberg
Source: Boston University
Contact: Jennifer Rosenberg – Boston University
Image: The image is credited to 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. DOI: 10.1016/j.cub.2026.03.057
Abstract
Songbird connectome reveals tunneling of migratory neurons in the adult striatum
Immature neurons generated in the adult brain migrate into established circuits and contribute to plasticity, learning, and complex behaviors. While molecular mechanisms and functional consequences of adult neurogenesis have been studied extensively, less is known about the physical interactions between migrating neurons and the mature microenvironment.
Using electron microscopy–based connectomics to examine the adult zebra finch striatum, researchers observed that migrating neurons contact a variety of structures, including axons, dendrites, synapses, and the somas of mature neurons. These interactions frequently produced marked deformations of somas and neuropil, appearing as tunnels carved by the migrating cells as they displaced mature structures along their path.
Overall, the findings indicate 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.