Scientists at The Hospital for Sick Children (SickKids) have made a groundbreaking discovery in the field of childhood memory development. Through a pioneering preclinical study, they have potentially identified the molecular basis for changes in memory during early childhood.
When we talk about memory, we often refer to event-based or episodic memories, which are linked to specific contexts. In contrast, young children typically have more general or “gist”-based memories that lack specific contextual associations.
In a recent publication in the journal Science, Drs. Paul Frankland and Sheena Josselyn, Senior Scientists in the Neurosciences & Mental Health program at SickKids, led a team of researchers who unraveled the molecular mechanisms behind the transition from gist-like to episodic memory in mice. Understanding this shift, which typically occurs between the ages of four and six in children, could shed light on child development research and various conditions affecting the brain, including autism spectrum disorder and concussion.
“For decades, researchers have explored the development of episodic memory, but thanks to precise cellular interventions, we were finally able to examine this question at the molecular level,” said Dr. Frankland, who also holds a Canada Research Chair in Cognitive Neurobiology.
The researchers discovered that the growth of a structure called the perineuronal net might trigger changes in memory. In adults, memory traces, known as engrams, consist of approximately 10 to 20 percent of neurons. However, in young children, engrams are twice the size, with 20 to 40 percent of neurons forming a memory engram.
So, what causes this change? The hippocampus, a region responsible for learning and memory, contains various types of neurons, including inhibitory cells known as parvalbumin-expressing (PV) interneurons. These interneurons regulate the size of engrams and enable memory specificity. The research team found that as these interneurons mature, memories transition from general to more specific, and appropriately-sized engrams are formed.
Using viral gene transfer technology developed by Dr. Alexander Dityatev, head of the Molecular Neuroplasticity research group at the German Center for Neurodegenerative Diseases, the researchers delved deeper into understanding this change. They discovered that as the perineuronal net, a dense extracellular matrix, develops around these interneurons in the hippocampus, the interneurons mature, leading to a shift in the formation and storage of engrams in our brains.
“By accelerating the development of the perineuronal net, we were able to create specific episodic memories, rather than general ones, in juvenile mice,” explained Dr. Josselyn, who holds a Canada Research Chair in Circuit Basis of Memory.
This groundbreaking research not only offers insights into brain function and cognition but also has implications for child development research. By accelerating the growth of the perineuronal net and facilitating the formation of specific memories, the study opens up new avenues for investigating child development at SickKids and the University of Toronto.
“In addition to memory development, we observed similar maturation-type mechanisms in different sensory systems of the brain,” added Dr. Frankland. “This suggests that the same brain mechanism may be employed by various brain regions for different purposes, presenting exciting opportunities for further research and collaboration.”
Reference: “A shift in the mechanisms controlling hippocampal engram formation during brain maturation” by Adam I. Ramsaran, Ying Wang, Ali Golbabaei, Stepan Aleshin, Mitchell L. de Snoo, Bi-ru Amy Yeung, Asim J. Rashid, Ankit Awasthi, Jocelyn Lau, Lina M. Tran, Sangyoon Y. Ko, Andrin Abegg, Lana Chunan Duan, Cory McKenzie, Julia Gallucci, Moriam Ahmed, Rahul Kaushik, Alexander Dityatev, Sheena A. Josselyn and Paul W. Frankland, 4 May 2023, Science.
This study received funding from Brain Canada, the Canadian Institutes of Health Research (CIHR), the University of Toronto, SickKids Research Institute, the German Research Foundation, the German Center for Neurodegenerative Diseases, the National Institutes of Health (NIH), Natural Sciences and Engineering Research Council of Canada (NSERC), Ontario Graduate Scholarship program, Ontario Trillium Scholarship program, and the Vector Institute.
Frequently Asked Questions (FAQs) about childhood memory development
What did the study conducted by the researchers at The Hospital for Sick Children uncover?
The study conducted by the researchers at The Hospital for Sick Children uncovered the molecular mechanisms underlying the transition from gist-like to episodic memory in childhood.
What type of memories are typically formed by young children?
Young children typically form more general or “gist”-based memories that lack specific contextual links, as opposed to event-based or episodic memories.
What is the role of parvalbumin interneurons in memory development?
Parvalbumin interneurons, a type of inhibitory cell in the hippocampus, regulate the size of engrams and enable memory specificity during development.
What triggers the change from gist-like to episodic memory?
The growth of the perineuronal net, a dense extracellular matrix surrounding the parvalbumin interneurons in the hippocampus, triggers the change from gist-like to episodic memory.
How did the researchers accelerate the development of specific episodic memories in mice?
Using viral gene transfer technology, the researchers accelerated the development of the perineuronal net, which led to the creation of specific episodic memories in juvenile mice.
What are the potential implications of this research?
The research may provide new insights into child development, as well as conditions affecting the brain, such as autism spectrum disorder and concussion. It could also contribute to understanding brain function and cognition in general.
More about childhood memory development
- The Hospital for Sick Children (SickKids): Website
- Science: Publication
- Alexander Dityatev: Research Group
- Canadian Institutes of Health Research (CIHR): Website
- University of Toronto: Website
- Brain Canada: Website
- German Center for Neurodegenerative Diseases: Website
- National Institutes of Health (NIH): Website
- Natural Sciences and Engineering Research Council of Canada (NSERC): Website
- Ontario Graduate Scholarship program: Website
- Ontario Trillium Scholarship program: Website
- Vector Institute: Website