Thesis defense Isabella Wagner (Donders series 252)

January 2017
Promotor: prof. dr. . Fernández, copromotor: dr. M van Buuren
On memory organization: Imaging memory representations during encoding, consolidation, and retrieval

In this thesis, I tried to answer the question of how memories are organized in the brain using fMRI to measure brain activation in healthy human subjects. First, my experimental work revealed the brain processes that form durable, long-lasting memories at encoding. Second, I showed that consolidation following learning is affected by catecholaminergic signaling, and that thalamo-cortical interactions appear to re-organize memory representations over time. I found that these dynamics specifically strengthen durable memories, while weak material is prone to decay and will eventually be forgotten. Lastly, I demonstrated that memory formation can be promoted and accelerated by prior knowledge, or schemas. As we remember, the different components of a schema are recombined into one memory representation and this process appears to be supported by the angular gyrus. These results on memory organization and durable memory formation might help to inform educational settings that thrive to provide optimal learning conditions for students. Lastly, research in this direction might yield a better understanding of memory-related diseases by comparing memory organization in healthy young subjects with mnemonic processing in elderly or patient populations, potentially providing biomarkers for early Alzheimer’s disease.