Theta oscillations linked to auditory informativeness and context disambiguation

Accurate predictions and the processing of prediction error signals can be important for efficient interaction with the auditory environment. In a reanalysis of data from Simal et al . (2021), who found that informative tones elicited increased N1 and P2 event-related potential components, we sought to identify electrophysiological indicators in the time–frequency domain associated with disambiguation of the hearing context and prediction of forthcoming stimulation. Participants heard two isochronous sequences of pure tones separated by a silent retention interval. A sequence could contain one, three, or five tones. Fifteen participants heard the three load conditions randomly intermixed. In this case, when sequence length was unknown, the second and fourth tone during encoding contained information allowing the prediction of another tone. Other participants heard the sequences blocked by sequence length, and the second and fourth tone of the sequences provided no new information (and hence were not informative). We used wavelet analysis and Hilbert transform methods to analyse the oscillatory activity related to tone informativeness. We found a significant increase in theta (4–7 Hz) amplitude following a tone that was informative and allowed prediction, in comparison with a tone that carried no predictive information. Previous work suggests increased theta amplitude is linked with task switching and an increase in cognitive control. We suggest informative tones recruit higher-level control processes involved in prediction of upcoming auditory events.