Rapid Neural Reorganization during Retrieval Practice Predicts Subsequent Long-term Retention and False Memory

Active retrieval can induce changes to the strength and content of a memory, yielding enhanced or distorted subsequent recall. But how consolidation influences these retrieval-induced seemingly contradictory outcomes remains unknown. Here we show rapid neural reorganization over eight runs of retrieval practice predicted subsequent recall. Behaviorally, retrieval practice boosted memory following a 24-hour (long-term) but not a 30-minute delay, and increased false memory at both delays. Long-term retention gains were predicted by multi-voxel representation distinctiveness in the posterior parietal cortex that increased progressively over retrieval practice. False memory was predicted by unstable representation distinctiveness in the medial temporal lobe during retrieval practice. Memory-related neural networks gradually reconfigured over retrieval practice, with the ventrolateral and medial prefrontal cortex acting as hubs for functional connections that predicted long-term retention gains and false memory outcomes respectively. Our findings demonstrate dynamic neural reorganization during retrieval practice, through which memories are arranged into discrete yet malleable representations for subsequent consolidation.