Temporal predictions as motor readouts of sensory predictions

When will I see something and what will it be? Temporal predictions are crucial for adaptive interaction with the environment and are typically accompanied by predictions about sensory content, yet these two types of "what" and "when" predictions are usually studied separately. Specifically, oscillatory phase-coupling (or "entrainment") has been proposed to align our neural sensitivity with likely moments of stimulus appearance, however these accounts ignore that predictions about when something will appear are usually accompanied by predictions about what it will be. Thus, temporal predictions may not enhance all sensory processing but rather modulate particular channels encoding predicted content. We here demonstrate oscillatory phase-coupling in vision and show how it relates to content-specific encoding. In a magnetoencephalography (MEG) study, participants observed rhythmic Gabors at 1.33 or 2 Hz with predictable orientations. They judged the timing or orientation of a delayed probe which manipulated the requirement to covertly maintain the sequence rhythm. We found sustained oscillatory phase-coupling to the entrained rhythm in motor areas specifically when participants judged stimulus timing, where its extent was associated with perceptual performance. Meanwhile, neural decoding revealed content predictions in early visual areas ("what") that fluctuated in line with temporal predictions ("when"). These temporally-specific content predictions appeared regardless of task instruction but were correlated and phase-aligned with the motor phase-coupling during timing judgements. These findings suggest that temporal predictions may be derived from motor readouts of temporally-specific sensory predictions, with broad implications for our understanding of entrainment and prediction, and how we represent time more generally.