A window opens. A code is absorbed. The window closes.
From birth through roughly age twenty-five, the human brain is not merely growing — it is being written. A new framework called the criticome, introduced by neuroscientists at Lausanne and SUNY Upstate, names this complete archive of sensory, social, and environmental experience absorbed during windows of peak plasticity, arguing that what enters during those windows becomes structural, and what does not cannot easily be added later. The framework reframes psychiatric conditions not as adult breakdowns but as failures of integration during the very periods when integration was possible. In an age when children are absorbing unprecedented volumes of screen-mediated experience during those same windows, the framework arrives less as an answer than as a precisely sharpened question.
- Decades of psychiatric research may have been asking the wrong question — focusing on what breaks in the adult brain rather than what was never properly built during childhood.
- Conditions like schizophrenia, autism, and depression are recast as developmental disorders, meaning the critical damage occurs during narrow windows of neuroplasticity that eventually close for good.
- Up to half of all cortical synapses are pruned away across childhood and adolescence — what is eliminated cannot be recovered, making the experiences absorbed during those years literally irreversible in their architecture.
- Screen-saturated childhoods represent the framework's most urgent open problem: today's children are absorbing screen-mediated experience at historically unprecedented scales during the precise windows when the brain is most malleable, with consequences still unknown.
- Researchers are now equipped with a testable empirical framework rather than a moral panic — the criticome gives scientists, clinicians, educators, and policymakers a shared vocabulary for questions they have long been asking separately.
Neuroscientists have long asked what breaks in the adult brain to produce psychiatric illness. A new peer-reviewed framework published in Brain Health proposes they have been asking the wrong question. The right one, according to Michel Cuenod, Kim Q. Do, and Julio Licinio, is what never got built in the first place.
Their framework, called the criticome, names the complete archive of sensory, motor, social, and environmental experience the brain integrates during critical periods of plasticity — from before birth through approximately age twenty-five. What enters during those windows becomes structural. What does not enter, or enters distorted, cannot easily be recovered afterward. An old proverb the authors invoke puts it plainly: an old parrot does not learn to speak.
The framework reshapes how psychiatry understands its major conditions. Schizophrenia, autism, PTSD, and major depression are recast not as adult synaptic failures but as disorders of integration — things that went wrong during windows that have since closed. A striking natural experiment with identical twins discordant for depression illustrates the point: with identical genes and shared family environments, the affected twin almost always carried a relational rupture that compounded slowly across decades, shaping the very neural scaffolding that adult mood regulation depends upon.
Six neurobiological mechanisms anchor the framework, including GABAergic interneuron regulation, perineuronal nets, myelination, epigenetic regulation, and synaptic pruning. Pruning receives particular emphasis: up to half of cortical synapses are eliminated across childhood and adolescence, and what is pruned is gone. The same plasticity that allowed Mozart to emerge from a childhood saturated in music also produced the developmental delays documented in Romanian orphanages — and, the authors note without flinching, was deliberately exploited by the Nazi Hitlerjugend.
Screen exposure is the framework's central open problem. Children today absorb screen-mediated experience at scales no previous generation has known, during the precise windows when the criticome is most malleable. The authors do not claim to know what kind of brain architecture is being assembled under those conditions. They argue the question is now urgent — and that the criticome finally gives researchers a way to study it rigorously rather than argue about it morally.
The review closes with a passage that lingers. Carl Jung, briefly treating Lucia Joyce in 1934, observed that she and her father James produced writing that looked nearly identical — ruptured syntax, coined words, logic that skipped its rails. One was among the century's greatest novelists. The other was his daughter, diagnosed with schizophrenia. Jung said they were like two people going to the bottom of a river, one falling and the other diving. The criticome offers a neurobiological reading of that asymmetry: Joyce navigated those depths by choice, from a brain whose critical periods had closed on intact integration. Lucia was drawn down without her consent, through windows that had closed on something else entirely.
Neuroscientists have a problem: they have been studying the wrong question. For decades, researchers investigating psychiatric illness have asked what breaks in the adult brain. A new framework, published as a peer-reviewed synthesis in Brain Health, suggests they should have been asking what never got built in the first place.
The framework is called the criticome, and it names something neuroscience has lacked precise language to describe. Michel Cuenod and Kim Q. Do at Lausanne University's Center for Psychiatric Neuroscience, working with Julio Licinio at SUNY Upstate Medical University, define it as the complete archive of sensory, motor, social, cultural, and environmental experience that the brain integrates during critical periods of synaptic plasticity—from before birth through approximately age twenty-five. What enters during those windows becomes structural. What does not enter, or enters distorted, cannot easily be added later. The authors are not claiming to have solved the riddle of screen-saturated childhoods. They are offering something more useful: a precise enough framework to study it.
The shift in perspective is most consequential when applied to psychiatry. Autism spectrum disorders, schizophrenia, post-traumatic stress, major depressive disorder, and culture-bound syndromes are no longer understood as purely synaptic breakdowns in adults. They are recast as developmental conditions—disorders of integration that occurred during windows when integration was possible and then closed. Schizophrenia, in this lens, is bound up with disrupted maturation of parvalbumin-positive interneurons in the prefrontal cortex during late adolescence. Autism reflects altered critical-period timing across multiple sensory and association systems. Early trauma rewires stress responsivity for life. "The data have been telling us for years that schizophrenia is a disorder of development, not a disorder of the adult synapse," Cuenod said. "The difficulty has always been articulating what went wrong, and when. The criticome gives us a frame for that question."
Major depression receives the review's most carefully argued case, drawing on a striking natural experiment by Kenneth Kendler and Lindon Halberstadt. They interviewed fourteen pairs of identical twins raised together but rigorously discordant for lifetime depression. With genotype identical and family environment shared, the affected twin almost always carried the weight of a relational rupture—sometimes by chance, sometimes channeled there by a slightly more impulsive temperament that hardened across decades into a divergent life. Kendler and Halberstadt called this slow magnification cumulative continuity. The criticome lens places that finding in a mechanistic frame: the social scaffolding integrated during the protracted late-adolescent prefrontal window is itself load-bearing for adult mood regulation.
Six neurobiological mechanisms anchor the framework: GABAergic regulation through parvalbumin-positive interneurons, perineuronal nets around fast-spiking cells, progressive myelination of cortical circuits, experience-dependent epigenetic regulation, neuromodulatory maturation, and developmental synaptic pruning. The authors treat pruning as a pillar rather than an afterthought. Up to half of cortical synapses are eliminated across childhood and adolescence, with microglia and complement-mediated tagging doing much of the work. What is pruned cannot be recovered. What is preserved becomes the substrate of adult cognition. An old Brazilian proverb captures what molecular biologists have since confirmed: an old parrot does not learn to speak. Hubel and Wiesel showed it in the cat visual system. Language acquisition, birdsong, attachment, the rough geography of moral feeling—the same logic runs through all of them. A window opens. A code is absorbed. The window closes. After that, acquisition is effortful and incomplete.
Critical periods are double-edged. The same machinery that allowed Mozart to emerge from a childhood saturated in harmonic relationship is the machinery that produced the developmental delays documented in Romanian orphanages. The progression from a toddler's first steps to Roger Federer on Centre Court rests on motor experience integrated during plastic windows. So does the contemplative architecture established when Lhamo Dhondup was recognized as the Dalai Lama at age two and immersed in meditative training from early childhood. The review also names the dark uses without flinching. The Nazi Hitlerjugend exploited critical-period plasticity by design. Current conflicts are integrating violence and displacement into the criticomes of children in real time, with consequences that will outlive their causes.
The review treats screen exposure as the central open problem of its framework. Contemporary children and adolescents are absorbing screen-mediated experience at scales no previous generation has known, during the precise windows when the criticome is most malleable. The authors do not claim to know what kind of criticome is being assembled under those conditions. They argue, persuasively, that the question is now urgent, and that the framework gives researchers a way to formulate it as a testable empirical problem rather than a moral panic. "We wrote this for the clinician asking the right questions without quite having the vocabulary," said Julio Licinio. "It is also for the educator wondering why second-language instruction works so much better at five than at fifteen, and for the policymaker trying to understand why early-childhood investment yields the returns it does. They are the same question."
One of the review's most evocative passages sets a sentence from Finnegans Wake beside a sentence from the letters of Lucia Joyce, James Joyce's daughter, diagnosed with schizophrenia. On the surface, the two read the same: ruptured syntax, coined words, associations that skip the rails of ordinary logic. One writer is among the most celebrated novelists of the twentieth century. The other was a patient. Carl Jung, who briefly treated Lucia in 1934, gave the sharpest answer on record. Father and daughter, he said, were like two people going to the bottom of a river, one falling and the other diving. The criticome offers a neurobiological reading of that asymmetry. Joyce composed from a criticome integrated under intact critical-period regulation, then chose, as an adult, to navigate its depths. Lucia's late-adolescent prefrontal window closed on a disrupted integration, and the same depths drew her down without her consent.
Citas Notables
The data have been telling us for years that schizophrenia is a disorder of development, not a disorder of the adult synapse. The difficulty has always been articulating what went wrong, and when. The criticome gives us a frame for that question.— Michel Cuenod, Center for Psychiatric Neuroscience, Lausanne University
We wrote this for the clinician asking the right questions without quite having the vocabulary. It is also for the educator wondering why second-language instruction works so much better at five than at fifteen, and for the policymaker trying to understand why early-childhood investment yields the returns it does. They are the same question.— Julio Licinio, SUNY Upstate Medical University
La Conversación del Hearth Otra perspectiva de la historia
Why does the field need a new word? Neuroscience already has language for development, for plasticity, for experience-dependent change.
Because those words describe pieces. The criticome names the whole—the complete integrated record that becomes the substrate of adult life. When a clinician sees a patient with schizophrenia, they have been trained to ask what is broken now. The criticome asks what could not be integrated then. Those are different questions with different answers.
And the authors are saying psychiatric conditions are developmental, not just synaptic. But aren't they both? Doesn't development build synapses?
Yes, but the distinction matters clinically. If schizophrenia is a disorder of the adult synapse, you treat the adult. If it is a disorder of late-adolescent prefrontal development, you are asking what happened during that window—what experience was missing or distorted. You cannot go back and redo adolescence. That changes what interventions are even possible.
The screen question seems almost secondary in the paper. Why is it the urgent one?
Because it is the only one we can still influence. The authors are not saying screens are destroying children's brains. They are saying we do not know what screens are building into the criticome, and we are running the experiment in real time on an entire generation. That is why the framework matters—it gives us a way to ask the question precisely instead of just worrying.
The Lucia Joyce passage—that seems like it could be misread as saying mental illness is just a choice, or a failure of will.
The opposite. Jung's metaphor is that the same depths exist in both minds. Joyce had the scaffolding to navigate them. Lucia did not. Her window closed on disrupted integration. She did not choose to fall any more than Joyce chose to dive. The criticome explains why the same territory produces genius in one and suffering in the other.