Before the defence, Elise Holter Thompson presented her trial lecture "Exceptional memory, being able to forget and reverse learning."
The PhD defence and trial lecture were fully digital.
Summary
How the brain balances between plasticity and stability to create and store memories remains elusive. While brain plasticity is massive in early life, it is reduced in adults. A specialized form of extracellular matrix, called perineuronal nets, enwraps neurons contributing to reduced plasticity. Removal of PNNs in adults reinstates high plasticity but their functional roles remain mostly unresolved.
In her doctoral work, Elise Thompson has used advanced experimental approaches to reveal the impact of PNNs on neuronal activity, behavior and memory processing.
To test the proposed role of PNNs to stabilise neural networks, Thompson and colleagues removed PNNs in adults after memory acquisition. Results showed that PNN removal led to amnesia, illustrating a role for PNNs in memory processing, perhaps by stabilising connections to other involved brain areas.
Furthermore, Thompson and colleagues investigated a mouse line with a genetic mutation disrupting PNN development. In a comprehensive evaluation, they found that these mice showed reduced levels of anxiety, with no other apparent changes to memory processing and neuronal activity.
The results from Elise Thompson’s work suggest that while acute loss of PNNs may have drastic consequences, such as amnesia, disrupting PNN development may allow unknown compensatory effects ensuring normal functionality.