India, June 4 -- Children's experiences may influence brain development far longer than previously appreciated. A new review published in Brain Health introduces the concept of the "criticome"-the complete collection of sensory, social, cultural, environmental, and learning experiences the brain absorbs during critical developmental periods from before birth through approximately age 25 (1).
The researchers note that modern influences such as screen time, alongside family, education, and social interactions, may become part of this lifelong developmental imprint.
According to the researchers, these experiences help shape how people think, learn, behave, and respond to the world throughout life.
The framework comes at a time when children's exposure to digital environments is increasing worldwide.
A systematic review and meta-analysis published in Cureus reported that children under five years of age in India spend an average of 2.22 hours per day on screens, exceeding the screen-time limits recommended by the World Health Organization (WHO) (2).
Researchers say such findings highlight the growing importance of understanding how early-life experiences influence long-term brain development.
What Is the "Criticome" and Why Does It Matter?
According to the Brain Health review, the criticome refers to the total record of sensory, motor, social, cultural, and environmental experiences that become embedded in the developing brain during periods of heightened plasticity.
These developmental windows begin before birth and continue into early adulthood, although the timing varies across different brain systems.
The authors argue that the criticome is more than memory. It includes the broader experiences that shape neural architecture during critical developmental stages.
These experiences may influence language, learning, relationships, emotional regulation, cultural identity, and lifelong behavior.
The framework highlights five major categories of experiences that become integrated into the developing brain:
Sensory experiences such as sights, sounds, touch, smell, and taste
Motor experiences involving movement and physical interaction
Social experiences including attachment and relationships
Cultural experiences such as language, beliefs, and traditions
Environmental experiences shaped by living conditions and surroundingsWhy Do Early Experiences Leave Lasting Effects on Mental Health?
The review proposes that many psychiatric conditions may originate from disruptions during critical developmental windows rather than from changes that occur only later in life.
Researchers suggest that the key question is not simply what is wrong in the adult brain, but whether important experiences were absent, altered, or incorrectly integrated during development.
According to the authors, autism may involve altered timing of critical developmental periods across sensory and communication systems.
Schizophrenia may be linked to disruptions in brain maturation during adolescence, particularly within the prefrontal cortex. Early-life trauma can also shape stress-response systems in ways that persist for decades.
The review also discusses evidence from studies of major depression.
Research involving identical twins found that despite sharing genes and family environments, the twin who developed depression often experienced significant relationship disruptions and life experiences that gradually shaped different developmental pathways.
The authors suggest that these accumulated experiences may become part of the criticome and influence long-term emotional health.How Does the Brain Decide What to Keep and What to Remove?
The Brain Health review identifies six biological mechanisms that help govern critical developmental periods:
GABAergic regulation involving parvalbumin-positive interneurons
Perineuronal nets that help control brain plasticity
Myelination, which strengthens communication pathways
Experience-driven epigenetic changes
Maturation of neuromodulatory systems
Developmental synaptic pruning
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Among these processes, synaptic pruning plays a particularly important role. During childhood and adolescence, the brain removes large numbers of unused neural connections while strengthening important ones.
Researchers note that what is preserved becomes the foundation for adult thinking and behavior, while connections that are removed are difficult to restore later.
The review describes this process as one of the ways the criticome becomes permanently embedded in brain architecture.
Are Screens Becoming a Major Influence on Childhood Development?
One of the central questions raised by the review concerns the growing role of digital environments.
Today's children spend far more time interacting with screens than any previous generation, often during the same developmental windows when the brain is most adaptable.
Importantly, the authors do not claim that screens are inherently harmful. Instead, they argue that scientists urgently need to understand how screen-based experiences contribute to the criticome and whether they influence long-term brain development.
Additional evidence suggests this question deserves close attention.
A recent review in Children analyzing 46 studies found that higher screen exposure was frequently associated with reduced physical activity, poorer sleep, attention difficulties, and challenges in emotional and social development.
However, the same review noted that educational and supervised screen use could sometimes provide benefits, depending on content and context (3).
Research published in Clinical Child Psychology and Psychiatry also found that adolescents often describe social media as a double-edged tool (4).
While it can support connection, peer support, and self-expression, it may also contribute to body-image concerns, social comparison, cyberbullying, anxiety, and pressure to remain constantly connected.
Could Experiences Before Birth Shape the Brain Too?
The criticome framework extends beyond childhood and suggests that development begins even before birth.
This idea aligns with findings from the NIH-supported HEALthy Brain and Child Development (HBCD) Study, which examines how prenatal and early-life experiences influence brain development (5).
Researchers note that biological, social, and environmental factors during pregnancy and early childhood can affect developmental trajectories for years to come.
The HBCD study highlights how factors such as nutrition, parental support, environmental conditions, stress, and early-life adversity may shape cognitive, emotional, and behavioral outcomes. Researchers hope that understanding these influences will help identify opportunities for earlier intervention and better mental health outcomes later in life.
What Does This New Framework Mean for Parents, Schools, and Healthcare?
The authors emphasize that the criticome is currently a conceptual framework rather than a clinical test. Scientists cannot yet measure a person's criticome directly, and much more research is needed before the concept can guide treatments.
Even so, the framework reinforces a growing scientific message: experiences during childhood, adolescence, and even prenatal development can have lasting effects on brain health. Education, relationships, culture, environment, stress, and digital exposure may all contribute to how the developing brain is shaped.
By providing a common framework for studying these influences, researchers hope the criticome concept will help scientists better understand why some experiences promote resilience while others increase vulnerability to mental health disorders later in life.