Neural substrates related to memory consolidation of learning multiple motor sequences during wakeful rest

Motor learning has long been considered independent of the hippocampus, but recent evidence suggests that the hippocampus contributes to motor memory consolidation during wakeful rest. However, whether hippocampal reactivation supports consolidation during interleaved rest remains unclear. We investigated the fMRI evidence of motor memory consolidation of learning multiple motor sequences during wakeful rest. We found that while sensorimotor regions exhibited sequence-specific activity patterns during practice, these were not reliably discriminable in the sensorimotor regions and hippocampus during interleaved rest. In contrast, neural activity patterns in the right hippocampus, right putamen, and sensorimotor regions during interleaved rest showed greater similarity to post-learning rest patterns than pre-learning rest patterns. These findings suggest that under highly interfering, multi-sequence learning conditions, the consolidation of motor memories may not be related to a specific sequence but may instead reflect a generalized or abstract representation of sequences, potentially to stabilize and minimize interference among newly acquired skills.