Revealing childhood memories through autism brain states

Immune activation shapes infant memory development.


Researchers from Trinity College Dublin found a link between early life memories and autism-related brain development. Their study shows that ‘infantile amnesia,’ forgetting early infancy memories, can be reversed and prevented. Typically, people recall very little from before age two. This memory loss, known as ‘infantile amnesia,’ involves forgetting episodic and autobiographical memories. The researchers from Trinity explored the impact of autism on this memory phenomenon.

The immune response of a mother during pregnancy, triggered by infection, has been linked to autism in both humans and mice. Trinity neuroscientists have now found that this altered immune response also prevents the usual loss of memories formed during infancy. Using a mouse model, the team demonstrated that exposure to maternal immune activation safeguards against developmental memory loss in early life. 

The study further showed that forgotten infant memories can be permanently reinstated in adults by activating specific memory cells using an ‘optogenetics’ approach involving light to trigger neural pathways linked to the targeted memories.

The study suggests that infantile amnesia occurs due to a retrieval deficiency. Even though early childhood memories are stored in the adult brain, they cannot be naturally accessed through recall. Dr. Tomás Ryan, the article’s senior author, is an Associate Professor at Trinity’s School of Biochemistry and Immunology and the Trinity College Institute of Neuroscience. The research has been published in the prestigious journal Science Advances.

Infantile amnesia, a widely overlooked form of memory loss in humans and mammals, has been a mystery regarding its biological basis and impact on memory-encoding cells. The research findings indicate that immune activation changes the brain state during pregnancy, influencing the ‘forgetting switches’ responsible for infantile amnesia. 

This challenges the assumption that forgetting early memories is unavoidable, suggesting it’s reversible. The study has important implications for understanding memory development and cognitive flexibility, particularly in autism.

Lead author of the study, Dr. Sarah Power, who completed her Ph.D. research in Dr. Ryan’s team (now a postdoctoral researcher at the Max Planck Institute for Human Development in Berlin, Germany), said:

“Our brains’ early developmental trajectories affect what we remember or forget as we move through infancy. We now hope to investigate in more detail how development affects the storage and retrieval of early childhood memories, which could have several important knock-on impacts from both an educational and a medical perspective.”

This study is a significant step in understanding developmental memory, revealing a link between retaining early childhood memories and maternal immune responses related to Autism Spectrum Disorder (ASD). It highlights the brain’s adaptability to environmental challenges during embryonic and early postnatal development. 

The research received support from various organizations, including the Jacobs Foundation, Science Foundation Ireland, European Research Council, Boehringer Ingelheim Fonds, Lister Institute of Preventive Medicine, Brain & Behavior Research Foundation, and the Canadian Institute for Advanced Research (CIFAR).

In conclusion, this study marks a crucial milestone in developmental memory research. Focusing on the interplay between autism brain states and childhood memory unlocking advances our understanding of how neurodevelopmental conditions may shape cognitive processes. The findings offer new perspectives on memory-related challenges associated with autism, paving the way for further exploration and potential interventions in developmental neuroscience.

Journal reference:

  1. Sarah D. Power, Erika Stewart etal., Immune activation state modulates infant engram expression across development. Science Advances. DOI: 10.1126/sciadv.adg9921.
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