Summary: Researchers engineered a highly specialized patterned stimulation protocol called REPOPS (Repeated Electroconvulsive-like Patterned Optical/Electrical Stimulation) in murine models to precisely mirror the neural activation patterns of ECT. The empirical data unmasked a stunning structural transformation: intensive ECT-like stimulation coaxes fully mature, non-dividing adult neurons to undergo an active process of cellular dematuration.
By entering a state of nuclear reprogramming driven unexpectedly by the cell-cycle protein Cyclin B, mature neurons fundamentally reshape their identity, winding back their genetic clocks to resemble highly plastic, early postnatal developmental states.
Key Facts
- The Cellular Dematuration Framework: Genome-wide transcriptomic profiling unmasked that REPOPS forces mature, fully differentiated adult neurons to suppress their adult genetic markers. Instead, they reactivate gene expression blueprints that match early postnatal development. Widespread genome-wide chromatin mapping confirmed long-lasting structural changes in chromatin accessibility, proving this youthful state is epigentically locked in place for over a month.
- Unexpected Post-Mitotic Cell Cycle Re-entry: The most jaw-dropping molecular discovery was that adult neurons, cells that are strictly post-mitotic and can never divide again, suddenly expressed gene networks typically reserved exclusively for the G2/M division phase of proliferating cells. The neurons displayed clear physical hallmarks of mitosis, including widespread histone phosphorylation, the breakdown of the nuclear lamina protective skin, and pronounced chromatin condensation.
- Cyclin B Isolated as the Molecular Driver: To prove this cell-cycle activation was driving the structural shift rather than acting as a random byproduct, Miyakawa’s lab deployed targeted genome-editing technology. Mice engineered to lack Cyclin B (the core molecular key required to cross the G2/M phase boundary) exhibited a total failure of nuclear reprogramming and showed zero behavioral improvements following stimulation, identifying Cyclin B as the absolute gatekeeper of ECT efficacy.
- The “Intermediate State” of Heightened Plasticity: Calcium-flux live imaging in actively behaving mice revealed that REPOPS does not simply act as an on/off switch for neural circuits. Instead, it coaxes the brain into a unique “intermediate state” of intense plasticity. The network completely shifted how it encoded information, selectively suppressing spatial coding maps while heavily boosting speed-related navigation tracking for over two weeks.
- Human Validation in the Dentate Gyrus: Transitioning from mice to humans, the team’s reanalysis of postmortem brain tissue from deceased patients with major depression revealed an identical biological footprint. Individuals who had undergone ECT treatments prior to their passing displayed the exact same immature-like gene expression patterns within the dentate gyrus (the primary gateway of the hippocampus) compared to non-ECT patients, confirming human translation.
- A Double-Edged Sword for Neurology: Professor Miyakawa emphasizes that this newly uncovered intermediate state is a powerful, highly flexible biological tool. While this extreme boost in structural plasticity is precisely what allows an injured brain to break free from severe depression, the team warns that if the exact same nuclear reprogramming occurs under incorrect or overly aggressive conditions (such as advanced neurodegeneration or epilepsy), it could spin out of control and drive severe pathology.
Source: Fujita Health University
Nearly 90 years after Ugo Cerletti and Lucio Bini introduced electroconvulsive therapy (ECT), brain stimulation therapies such as ECT and Repetitive Transcranial Magnetic Stimulation (rTMS) are common in psychiatry because they are highly effective for treating depression and schizophrenia, yet their cellular mechanisms remain poorly understood.
The team introduced REPOPS, a form of patterned stimulation in mice designed to mimic key features of ECT-like neuronal activation.
Mice subjected to REPOPS showed increased locomotor activity and reduced depression-like behavior, revealing stimulation-induced lasting behavioral changes similar to ECT-like states. At the cellular level, the stimulation induced a state of cellular dematuration, in which adult neurons had gene expression patterns resembling those seen in early postnatal development.
Stimulation for three days caused only transient changes, while ten-day stimulation resulted in a stable dematuration state that persisted for over a month. Genome-wide chromatin mapping revealed widespread and persistent changes in chromatin accessibility, providing molecular evidence for the durability of this state.
A reanalysis of postmortem brain RNA-seq data from patients with mood disorders showed that ECT-treated individuals exhibited a similar immature-like gene expression pattern in the dentate gyrus compared to non-ECT-treated patients, suggesting that similar immature-like changes may also occur in the human dentate gyrus after ECT.
Surprising Emergence of Cell Cycle Re-entry in Mature Neurons
A gene expression analysis revealed an unexpected finding: despite being post-mitotic (cells that no longer divide), neurons following REPOPS exhibited gene expression patterns characteristic of the G2/M phase of the cell cycle in dividing cells, accompanied by nuclear hallmarks of mitosis — histone phosphorylation, disruption of the nuclear lamina, and chromatin condensation.
These molecular and structural changes suggested nuclear reprogramming. Using genome-editing technology, the researchers demonstrated that mice lacking Cyclin B, a key molecular regulator of the G2/M phase transition, showed less nuclear reprogramming and behavioral changes, identifying it as a driver of cellular state triggered by neuronal stimulation.
An Intermediate State of Heightened Plasticity
The researchers next asked how nuclear reprogramming affects neuronal function. They used microscopic imaging of calcium fluxes, a proxy for neuronal activity, in behaving mice. Curiously, REPOPS did not simply turn neuronal activity on or off. Instead, it produced a patterned shift in how neurons encode different types of information — spatial coding was suppressed while speed-related coding was enhanced — that persisted for over two weeks.
Taken together, these molecular, nuclear structural, and functional findings led the researchers to propose that the dematured cellular state induced by ECT-like stimulation represents an “intermediate state” of high plasticity — neither the normal mature state nor the fully immature one — where the specific configuration may depend on how strongly, how often, and under what conditions neuronal activity is applied. The plasticity supporting therapeutic effects in depression could, under different conditions such as epilepsy or neurodegeneration, contribute to pathology instead.
“Nuclear reprogramming — the ability of neurons to fundamentally reshape their own identity — is a candidate mechanism we had not previously considered,” said Prof. Miyakawa. “These findings provide a new cellular framework for thinking about how durable changes in neural function can arise, and they offer a potential route to improved therapies.”
Key Questions Answered:
A: This is what makes Professor Miyakawa’s discovery an absolute shock to traditional biology. For decades, neuroscience has taught that once a neuron reaches maturity, it becomes permanently post-mitotic, meaning it locks its cell-division machinery away forever. If a mature neuron attempts to force its way through cell division, it typically triggers immediate cell death. The REPOPS framework proves that neurons can cleverly hijack the early stages of this division machinery (the G2/M phase) without actually completing the physical split. They use proteins like Cyclin B to intentionally soften their internal structure, break down their nuclear lining, and loosen up their packed DNA. They aren’t trying to duplicate; they are using the tools of cell division to perform a massive, structural house clean, allowing them to rapidly rewrite their active genes.
A: Think of severe, chronic depression like a deep, frozen rut in a muddy road. Over months or years of illness, the adult brain’s neural connections become incredibly rigid, locking negative emotional paths in place. “Cellular dematuration” is the biological equivalent of melting that frozen mud back into soft clay. By forcing adult neurons to temporarily express genes that look exactly like those found in a newborn baby’s brain, ECT-like stimulation strips away this unhealthy structural rigidity. The neuron doesn’t lose its long-term identity, but it enters an open, highly sensitive “intermediate state” of intense plasticity. This sudden malleability gives the brain a vital window to wipe away the rigid, depressive neural ruts and wire up entirely new, healthy pathways.
A: The live calcium-flux imaging in behaving models provided a fascinating answer to this concern. The treatment does not act like a chaotic eraser that turns off neural signaling across the board. Instead, entering this high-plasticity intermediate state causes the brain to elegantly pivot how it processes information. For instance, the researchers observed that while the neurons temporarily suppressed their spatial layout maps, they simultaneously cranked up their sensitivity to tracking speed. The brain remains active and functional, but its processing modes are temporarily shifted. Because the study showed these changes spontaneously stabilize and return to an adult baseline after a month, it confirms that the brain undergoes a structured, temporary transition rather than permanent damage.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- Journal paper reviewed in full.
- Additional context added by our staff.
About this neuroscience research news
Author: Hisatsugu Koshimizu
Source: Fujita Health University
Contact: Hisatsugu Koshimizu – Fujita Health University
Image: The image is credited to Neuroscience News
Original Research: Open access.
“Repetitive Neuronal Activation Regulates Cellular Maturation State via Nuclear Reprogramming” by Tomoyuki Murano, Hideo Hagihara, Katsunori Tajinda, Keizo Takao, Yoshihiro Takamiya, Kaoru Katoh, Alfred J. Robison, Mitsuyuki Matsumoto, Masakazu Namihira & Tsuyoshi Miyakawa. Nature Communications
DOI:10.1038/s41467-026-74202-w
Abstract
Repetitive Neuronal Activation Regulates Cellular Maturation State via Nuclear Reprogramming
Neural stimulation, such as electroconvulsive therapy (ECT) and repetitive transcranial magnetic stimulation (rTMS), is highly effective clinical intervention for a broad spectrum of psychiatric disorders, including depression and schizophrenia. However, their mechanism of action at the cellular level remains poorly understood.
Here, we model ECT with repeated optogenetic neuronal stimulation in the mouse dentate gyrus, and observe ECT-relevant behavioral changes, including decreased depression-like behavior and increased locomotor activity.
At the cellular level, we identify dematuration to a long-term stable state, persisting for more than one month, defined by changes in nuclear structure, gene expression patterns resembling the G2/M phase of the cell cycle, and altered neural coding of navigational information. Moreover, knockout of the G2/M master regulator Cyclin B attenuates some of behavioral and cellular effects.
These findings demonstrate that chronically-repeated brain stimulation triggers plasticity of the cellular state, revealing a form of stimulus-regulated nuclear reprogramming with potential clinical utility.
