Neural signatures of temporal regularity and recurring patterns in random tonal sound sequences

The auditory system is highly sensitive to recurring patterns in the acoustic input – even otherwise unstructured material, such as white noise or random tonal sequences. Electroencephalography (EEG) research revealed a characteristic negative potential periodically - response, which has been interpreted memory trace-related and specific, rather than sign of periodicity-driven entrainment. Here, we aim disentangle these two possible contributions by investigating influence periodic sound sequence's inherent temporal regularity on event-related potentials. Participants were presented continuous sequences short tones pitch, with some containing pattern, asked indicate whether they heard repetition. Patterns either spaced equally across sequence (isochronous condition) jitter (jittered condition), enabled us differentiate between potentials (and thus processing operations associated trace for repeated pattern) nature repetitions. A recurrence-related component could be observed independently regularity, was pattern-specific, modulated trial repetition pattern. Critically, isochronous pattern induced an additional early periodicity-related positive component, started build up already before onset elicited undampedly when occasionally not presented. This likely reflects sensory driven entrainment process that foundation behavioural benefit detecting temporally regular