Reduced low‐frequency power and phase locking reflect restoration in the auditory continuity illusion

Abstract

Interruptions in auditory input can be perceptually restored if they coincide with a masking sound, resulting in a continuity illusion. Previous studies have shown that this continuity illusion is associated with reduced low-frequency neural oscillations in the auditory cortex. However, the precise contribution of oscillatory amplitude changes and phase alignment to auditory restoration remains unclear. Using electroencephalography, we investigated induced power changes and phase locking in response to 3 Hz amplitude-modulated tones during the interval of an interrupting noise. We experimentally manipulated both the physical continuity of the tone (continuous vs. interrupted) and the masking potential of the noise (notched vs. full). We observed an attenuation of 3 Hz power during continuity illusions in comparison with both continuous tones and veridically perceived interrupted tones. This illusion-related suppression of low-frequency oscillations likely reflects a blurring of auditory object boundaries that supports continuity perception. We further observed increased 3 Hz phase locking during fully masked continuous tones compared with the other conditions. This low-frequency phase alignment may reflect the neural registration of the interrupting noise as a newly appearing object, whereas during continuity illusions, a spectral portion of this noise is delegated to filling the interruption. Taken together, our findings suggest that the suppression of slow cortical oscillations in both the power and phase domains supports perceptual restoration of interruptions in auditory input.

Low-frequency oscillations reflect aberrant tone restoration during the auditory continuity illusion in schizophrenia

“…Finally, the 3-4 Hz power increase was dampened when participants perceived a continuity illusion versus when they perceived an interruption. These findings were replicated, to a large extent, in a recent study by Kaiser et al (2018), who investigated induced power changes and phase locking in response to 3 Hz amplitude-modulated tones during the interval of an interrupting noise. Again, the authors observed an attenuation of 3 Hz power during continuity illusions in comparison to both continuous tones and veridically perceived interrupted tones.…”

“…Given previous findings of attenuated low-frequency oscillations during auditory processing in ScZ (Doege et al, 2009;Brockhaus-Dumke et al, 2007), we expected perceptually relevant alterations in 3 Hz power during the ACI paradigm in patients. Behavioral and EEG data for the control group have been previously described by Kaiser et al (2018). The present study constitutes an important extension of this study with a focus on the examination of differences and commonalities in auditory restoration during the ACI paradigm between patients with ScZ and healthy controls.…”

“…Electroencephalography (EEG) studies exploring the neural dynamics of auditory restoration during the ACI in healthy individuals have emphasized the role of lowfrequency oscillatory activity (Riecke et al, 2009(Riecke et al, , 2012Shahin et al, 2012;Kaiser et al, 2018). An EEG study in healthy individuals investigating oscillatory activity in the ACI employed 3 Hz amplitude-modulated tones that were either interrupted or continuous (Riecke, et al, 2009).…”

Orchestration of brain oscillations: principles and functions

“…The study by Kaiser et al . () suggests a multi‐faceted role for low‐frequency power in auditory perception: a desynchronization of theta over central electrodes could be involved in processes related to restoration of an interrupted sound, whereas its increase could be reflective of detecting auditory boundaries. On the other hand, the study by Moris Fernandez et al .…”

Investigating functional changes in the brain to intermittently induced auditory illusions and its relevance to chronic tinnitus

“…The most compelling finding of the current study is the significant positive relationship between ZT intensity rating and single‐trial theta power showing that ZT illusions may be related to changes in higher‐order processing systems such as sensory gating and auditory memory recall. A link between changing low‐frequency oscillations and perception of auditory illusions has been shown in a recent study by Kaiser and colleagues (Kaiser, Senkowski, Roa Romero, Riecke, & Keil, ). In this article, they show that reduced theta power goes together with the perceptual restoration of a tone when a temporal gap is masked by adding noise.…”