Summary: A new study shows that hibernation produces rapid, reversible changes in the brain’s visual cortex—demonstrating a form of neuroplasticity that allows neurons to withstand extreme metabolic shifts. By mapping how specific neuron types in ground squirrels respond during deep torpor and brief arousal, researchers uncovered a mechanism that fully reverses within 90 minutes of waking and leaves no detectable long-term damage. These findings point to potential strategies for promoting rapid neural recovery after injuries such as stroke.
Previous work had documented hibernation-related structural changes in somatosensory regions. This study extends that view to the primary visual cortex (V1), revealing that neuroplasticity during hibernation is both target-specific and remarkably fast: one population of neurons retracts its dendritic arbor during deep sleep and regrows it within about 1.5 hours after arousal, while another population remains stable throughout. Importantly, assessments months later showed no lasting structural deficits.
Key facts
- Focused visual mapping: Researchers examined V1—the first cortical station for visual information—to test whether the large structural changes seen in touch-processing regions also occur in the visual system.
- Cell-type specificity: Two distinct neuron types were tracked in V1. Layer 2/3 pyramidal neurons showed large, transient reductions in dendritic length, branching, and complexity during torpor; layer 4 spiny stellate neurons did not change.
- Rapid reversibility: Dendritic arbors in affected neurons regained their original size and complexity within approximately 90 minutes of natural arousal from deep hibernation.
- No long-term deficits: Structural comparisons made six months after the hibernation season found no detectable differences between animals that hibernated and those that did not.
- Translational potential: The speed and magnitude of this naturally occurring neuroplasticity make V1 in ground squirrels an appealing model for investigating mechanisms that could be harnessed to support faster recovery after stroke or other neural injuries.
Source: SfN
Why this matters: Understanding how hibernation alters neurons helps explain how brains tolerate extreme metabolic suppression and recover rapidly. If the molecular triggers behind this reversible remodeling can be identified and safely mimicked, they may enable new therapies that increase adult human brain plasticity during recovery from stroke or other forms of neural damage.
In a Journal of Neuroscience paper led by Hendrikje Nienborg at the National Eye Institute, researchers used the thirteen-lined ground squirrel (Ictidomys tridecemlineatus) to examine morphology changes in V1. They compared Golgi-stained neurons from hibernating and non-hibernating animals, sampling brains during deep torpor and during brief, periodic inter-torpor arousals.
The major morphological effect was a decrease in dendritic arborization of layer 2/3 pyramidal cells during torpor—shorter dendrites with fewer branches and reduced complexity. During inter-torpor arousal, those dendrites regrew quickly: on average the dendritic arbors increased by about 0.75 mm (roughly 65%) over approximately 1.5 hours. Layer 4 spiny stellate neurons showed no comparable changes, indicating that hibernation-related plasticity can be cell-type and area-specific rather than uniform across cortex.
Follow-up comparisons conducted six months after the hibernation season found no persistent structural differences between animals that had undergone hibernation and those that had not. That absence of long-term deficits suggests the remodeling is a reversible, protective adaptation rather than a degenerative process.
Nienborg and colleagues plan to extend this work by measuring functional consequences of these rapid structural rearrangements—how they affect synaptic communication, sensory processing, learning, and resilience to injury. As Nienborg notes, uncovering the biochemical signals and cellular machinery that permit such swift, safe remodeling could inform strategies to boost human brain plasticity after stroke.
Questions answered
Q: Why would a squirrel’s brain alter neuron structure during hibernation?
A: Hibernation requires dramatic energy savings. By temporarily retracting the dendrites of specific neuron populations, the brain can lower the metabolic cost of maintaining active synaptic networks while preserving the overall architecture needed for full recovery when the animal arouses.
Q: How can the brain restore structure so quickly?
A: The study shows that some hibernators possess biological triggers that allow rapid re-extension and branching of dendrites during arousal. This switch-like capacity contrasts with the slow rewiring typically seen in injured human brains and suggests specialized molecular mechanisms that rapidly rebuild synaptic scaffolds.
Q: How might this research help stroke patients?
A: Stroke damages neurons by depriving them of oxygen and nutrients. If researchers can identify the signals that enable rapid, reversible remodeling in hibernators—signals that protect neurons and restore connectivity—they may be able to develop therapies that enhance plasticity and recovery after stroke in humans.
Editorial notes
- This article was edited by a Neuroscience News editor.
- The Journal of Neuroscience paper was reviewed in full by the editorial team.
- Additional context and clarifications were added by staff.
About this research
Author: SfN Media
Source: SfN
Contact: SfN Media – SfN
Image credit: Neuroscience News
Original Research: Open access. DOI: 10.1523/JNEUROSCI.0077-26.2026
Authors: Allison Fultz, Carlos A. Mejias-Aponte, Christina Jacob, Laura Castillo, Francisco M. Nadal-Nicolas, Gao Yue, Wei Li, Hendrikje Nienborg. Journal of Neuroscience.
Abstract (summary):
Hibernating mammals display seasonal neuroplasticity. In ground squirrels, prior studies reported dendritic reductions across hippocampus, somatosensory cortex, and thalamus during torpor. This study characterizes similar plasticity in primary visual cortex (V1). Using Golgi-stained tissue from male and female thirteen-lined ground squirrels sampled during torpor and inter-torpor arousal, researchers found decreases in dendritic length, branch number, and complexity of V1 layer 2/3 pyramidal neurons during torpor, with full reversal during arousal. No morphological differences between hibernating and non-hibernating animals were detectable six months later. Layer 4 spiny stellate neurons showed no torpor-related changes. These findings support a brain-wide but area- and cell-type-specific mechanism of hibernation-related neuroplasticity and position ground squirrel V1 as a promising model for translational studies targeting rapid neural recovery.