Alpha power indexes working memory load for durations

Estimating and comparing how long events last requires the temporary storage of durations. How durations are stored in working memory is unknown, despite the central role of memory systems in timing. We investigated the neural signatures of working memory for sequences of durations with magnetoencephalography (MEG) while human participants performed an n-item delayed reproduction task. Sequences orthogonally varied in the number of items (one or three) and their durations. The number of durations in the sequence, but not the duration of the sequence, affected recall precision and could be decoded from alpha and beta oscillatory activity during retention. Our results extend earlier behavioral findings, suggesting that durations are itemized in working memory and that their number, not their duration, modulates recall precision. Crucially, we establish that alpha power reflects a universal signature of working memory load and mediates recall precision, even for abstract information such as duration.