Tracking the neural footprints of memories over time
Our memories are not simple snapshots of past experiences. Remembering is a highly reconstructive process, and each attempt to retrieve a past event can adaptively change the underlying memory space. In this talk, I discuss my work on the neurocognitive mechanisms that enable the selective retrieval of episodic memories. I present behavioural and electrophysiological (M/EEG) work that provides insight into how a memory trace unfolds in time during retrieval, on a sub-trial scale. These studies show that on a fast, sub-trial time scale, memory signatures (a) rhythmically fluctuate, and (b) prioritize meaningful conceptual over detailed perceptual information. Further, I show evidence from a series of fMRI studies in which we track the representational changes that occur in a memory trace over time and across repeated retrieval attempts. These findings demonstrate that retrieval adaptively modifies memories by strengthening behaviourally relevant and weakening behaviourally irrelevant and potentially interfering components. Together, this work sheds light onto the temporal dynamics and the adaptive natures of the memory reconstruction process.