Abstract
Temporal expectations (e.g., predicting “when”) facilitate sensory processing, and are suggested to rely on entrainment of low frequency neural oscillations to regular rhythmic input, such as a beat in music (“beat-based” expectations). However, temporal expectations can also be based on predictable repeated patterns (“pattern-based” expectations). These two types of expectations often occur simultaneously, but whether they are subserved by the same neural mechanisms is currently a topic of active debate. Here, we addressed this outstanding issue by examining EEG activity and behavioral responses during silent periods following rhythmic auditory sequences designed to elicit only beat-based or pattern-based expectations, or with random timing. In Experiment 1 (N = 32), participants rated how well probe tones at various time points fitted the previous rhythm. Beat-based expectations affected fitness ratings for at least two beat-cycles, while the effects of pattern-based expectations subsided after the first expected time point in the silence window. In Experiment 2 (N = 27), using EEG, we found a Contingent Negative Variation (CNV) following the final tones of pattern-based, but not beat-based sequences. Moreover, we found enhanced power in the EEG signal at the beat frequency for beat-based sequences both during listening and the silence, while for pattern-based sequences, enhanced power at a pattern-specific frequency was only present during listening, not during the silence. Finally, we show how multivariate pattern decoding and multi scale entropy – measures sensitive to non-oscillatory components of the signal – can be used to probe temporal expectations. Taken together, we show that beat-based and pattern-based expectations affect behavior differentially, with beat-based expectations exerting longer-lasting effects than pattern-based expectations. At a neural level, climbing activity may specifically reflect pattern-based expectations, while persistent low frequency oscillations may be specific to beat-based expectations. When studying responses to complex rhythmic stimuli, like in music and language, both types of expectations should therefore be considered.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
FLB is supported by an ABC Talent Grant awarded by Amsterdam Brain and Cognition, a Veni grant awarded by the Dutch Research Council NWO (VI.Veni.201G.066), and the ERC starting grant awarded to HAS. HAS is supported by a European Research Council (ERC) starting grant (679399).