Repeated beta transcranial alternating current stimulation disrupts consolidation and retention of motor sequence learning

Repeated beta-tACS tended to improve acquisition, but impaired consolidation and retention. This stage-specific disruption - preserved early learning followed by later deficits - supports a dynamic role for beta oscillations: early desynchronization facilitates flexible encoding, while later synchronization stabilizes learned patterns. Recovery during random blocks suggests transient disruption of motor flexibility followed by compensatory adaptation, rather than premature overgeneralization of sequence knowledge.