Effect of rhythm-based prediction on medial olivocochlear reflex and delta oscillations

Abstract

The medial olivocochlear reflex (MOCR) is an efferent feedback activated by acoustic stimulation. Our previous studies showed that a preceding sound expedites MOCR, which suggests that temporal expectation about the timing of stimulus occurrence can modulate MOCR. In contrast, the temporal structure, e.g., regularity and rhythm, of preceding sequences also contains cues for temporal expectation about the timing of upcoming sounds. Here we investigate whether the regularities of preceding sound sequences can modulate MOCR. Simultaneously, we measured electroencephalography (EEG) delta-band oscillations whose phase-locking was reported to play a role in mediating the effects of anticipation on target detection. The predictability of target occurrence was modulated by adding jitter to the inter-stimulus interval (ISI) of the preceding sound sequence. Both the strength of MOCR and the phase synchronization of EEG delta oscillations decreased with increasing the jitter up to 20% of the ISI and are saturated above that percentage. The similar dependence on the amount of the jitter suggest the involvement of delta oscillations in the predictive control of MOCR based on the regularity of preceding sound sequences.