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Isabel Wilder, Winner of the 2023 NIMH Three-Minute Talks Competition

Transcript

Hello everyone. My name is Destiny Wright. 

Working memory can be thought of as the brain’s sticky notes allowing us to briefly hold and manipulate information. We use it to plan and carry out everyday tasks, such as making a list of chores or remembering bedtime routines, which as we know are things that young children really struggle with.

Fortunately, as children grow, work and memory capacity greatly improves when they go through puberty. This crucial developmental milestone is associated with significant physical, behavioral, and emotional changes. It's also during this period that we often see the emergence of neuropsychiatric disorders like schizophrenia and depression, which are both linked to working memory impairments. 

In adults, two brain regions - the dorsal lateral prefrontal cortex and the hippocampus - are vital for proper working memory function, but in different ways. Specifically, as working memory demands increase the dorsal lateral prefrontal cortex is more engaged while the hippocampus is more suppressed in adults. However, it remains unclear how these important brain regions develop over puberty to resemble adult patterns. 

I have the amazing opportunity to work on an NIMH longitudinal study of healthy brain development across puberty, where we have the privilege to follow and study the same group of healthy children every nine months from age eight to 18 years old. At each visit, while in an MRI scanner, the children performed a working memory task that is already difficult for adults, but is especially hard for their developing brain. 

The task probed the activities of the dorsal lateral prefrontal cortex and the hippocampus, the two key brain regions for working memory. In the task, children indicated whether the current X on the screen matched this position two Xs ago. My goal was to examine the developmental patterns of the dorsal lateral prefrontal cortex and the hippocampus and boys and girls across puberty to determine if and when the activities in these regions became similar to adult patterns.

I found that with increasing age as shown on the X axis, boys and girls showed increased engagement of the dorsal lateral prefrontal cortex indicated by the positive values on the Y axis. While boys and girls start off with similar engagement, boys have a faster increase than girls during this critical time. In addition, boys and girls showed increased suppression of the hippocampus as they aged reflected by negative values on the Y axis. 

Interestingly, while girls began this hippocampal suppression at or prior to age eight, boys don't start until age 12, in the middle of puberty. In both regions, boys and girls tended to move towards the adult patterns we typically see in working memory. 

Our preliminary findings may contribute to our understanding of the emergence of neuropsychiatric disorders related to working memory impairments during adolescence. Given the hormonal fluctuations during this critical period, future research will explore the relationship between sex hormones and how they affect working memory-related brain development. 

Thank you.