Researchers have identified a molecular mechanism that helps explain why growing up in a stimulating environment enhances memory. In contrast, a lack of stimulation can impair it. The team from the Institute for Neurosciences (IN), a joint research center of the Spanish National Research Council (CSIC) and Miguel Hernández University of Elche (UMH), was led by researcher Ángel Barco.
Their study, conducted in mice and published in Nature Communications, demonstrates that the environment during childhood and adolescence has a lasting impact on the brain by activating or repressing a single transcription factor, AP-1, which regulates the expression of genes involved in neuronal plasticity and learning. This finding identifies a molecular mediator that can translate life experiences into persistent changes in cognitive function.
Mice raised in enriched environments
To carry out the research, the team from the IN’s Transcriptional and Epigenetic Mechanisms of Neuronal Plasticity laboratory raised young mice in three different conditions: an enriched environment with toys, exercise wheels, and social interaction; a standard environment; and an impoverished environment characterized by isolation and a lack of stimulation. After several weeks, animals raised in enriched environments showed superior performance in learning and memory tasks, whereas those reared in impoverished environments scored lower on cognitive tests.
Using advanced genomic and epigenetic techniques to analyze the brain, the researchers observed that early-life experiences produce long-lasting modulation of AP-1 activity: its activation boosts gene networks that strengthen neuronal connections, while reduced activity weakens those same processes.
To functionally validate this finding, the team experimentally blocked the Fos gene, one of the essential subunits of the AP-1 complex. Under these conditions, mice did not benefit from the enriched environment. They showed no cognitive improvement—demonstrating that AP-1 is not only correlated with environmentally induced changes in the brain but is also required for them to occur.
Implications for memory and brain development
“We have known for decades that the early-life environment influences learning capacity, but we lacked a clear mechanism to explain how this happens. We have now identified a molecular switch that translates those early experiences into long-lasting changes in the brain,” explains Barco.
“What is striking is that a single transcription factor acts as a convergence point for such diverse experiences as sensory stimulation, exercise, or social interaction. It is a key piece in understanding how the environment shapes memory,” notes the study leader.
The study also reveals that environmental impact varies among neuronal populations. By analyzing specific types of neurons, the scientists found that AP-1 responds differently in CA1 pyramidal neurons and in dentate gyrus granule cells, two key populations involved in spatial learning and memory formation.
According to Marta Alaiz-Noya, co-first author of the study together with Federico Miozzo and Miguel Fuentes Ramos, “the robust activation of AP-1 in enriched environments triggers gene programs that allow the brain to enter ‘learning mode,’ reinforcing neuronal connections during particularly sensitive developmental stages.”
“Taken together, these findings reinforce the idea that environmental stimulation and social interaction during childhood and adolescence not only enrich life experience but also leave a tangible biological trace in the brain. Moreover, they open the door to future therapeutic strategies that mimic the effects of enriched environments in neurodevelopmental disorders or in conditions involving cognitive decline,” adds Miozzo. https://medicalxpress.com/news/2025-12-molecular-links-early-life-memory.html
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