Our memories are not static. Each attempt to retrieve a past event from long-term memory is a complex and dynamic process, and adaptively changes the underlying memory trace. Recent research has successfully used multivariate pattern analysis to track the reactivation of mnemonic "snapshots" in human brain activity. I here focus more on the temporal dynamics and the adaptive nature of memory retrieval. I present behavioural and electrophysiological work that provides first insights into how the retrieval process unfolds in time, on a sub-trial scale. The findings suggest that neural reactivation starts very early after the presentation of a reminder, and that different elements (e.g. perceptual features, semantic content) of a past event are reactivated at different time points during retrieval. 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 retrievals, on cross-trial time scale. The findings demonstrate that retrieval adaptively modifies memories by strengthening behaviourally relevant, and weakening behaviourally irrelevant or interfering components. Together, this work sheds light onto the neural dynamics of the retrieval process, and informs theories of adaptive memory.