Encoding Memories in the Brain

People are constantly exposed to new experiences. One of our brain’s jobs is to store these experiences in a way that enables us to remember them in the near and distant future. Properly storing our past experiences as long-lasting memories is a crucial part of our ability to learn from the past and make useful (and hopefully correct) decisions in the future.

And yet, the mechanisms of how such memory traces are encoded and stably stored within brain networks remain only partially understood. There is robust evidence that at least some forms of memory are stored in so-called engrams, representing long-lasting changes in the neural structure and connectivity among nerve cells in certain brain regions.

Neuroscientist Sheena Josselyn showed that cells that are distinctly activated by certain experiences (for example through fear) indeed encode the information of such experiences to form stable memories. Her research demonstrates that experimental ablation or electrical silencing of such neurons, which are part of the engram, altered fear memory in mice and therefore provided direct evidence that the encoding of memories into engrams is a critical part of certain forms of learning and memory.

The hope is that future research will be able to translate the basic mechanisms that underlie our learning and memory – identified by Josselyn and her team as well as others – into novel approaches that can help us understand and eventually treat human neuropsychiatric diseases associated with impaired memory function, for example Alzheimer’s disease.

For her seminal discoveries in the context of molecular and cellular processes underlying memory formation, Professor Sheena Josselyn was awarded the 2023 award of the Betty and David Koetser Foundation for Brain Research. The award was presented during the annual symposium of the Zurich Neuroscience Center (ZNZ).