Expectancy changes the self-monitoring of voice identity

Abstract

Self-voice attribution can become difficult when voice characteristics are ambiguous, and functional magnetic resonance imagines (fMRI) investigations of such ambiguity are sparse. We utilized voice-morphing (self-other) to manipulate (un-)certainty in self-voice attribution in a button-press paradigm. This allowed investigating how levels of self-voice certainty alter brain activation in regions monitoring voice identity areas and unexpected changes in voice playback quality. FMRI results confirm a self-voice suppression effect in the right anterior superior temporal gyrus (aSTG) when self-voice attribution was unambiguous. Although the right inferior frontal gyrus (IFG) was more active during self-generated voice compared to when passively-heard, the putative role of this region in detecting unexpected self-voice changes was not confirmed. Further research on the link between right aSTG and IFG is required and may establish a threshold monitoring voice identity in action. The current results have implications for a better understanding of an altered experience of self-voice feedback leading to auditory verbal hallucinations.

Phonological and temporal regularities lead to differential ERP effects in self- and externally generated speech

“…The paradigm (adapted from Johnson et al, 2021; Ott & Jäncke, 2013) consisted of three conditions (Figure 2A). In all three conditions, the trial began with the presentation of a fixation cross, followed by a cue (< left, > right) at 0.4 – 1.0 s after trial onset.…”

“…MIS is modulated by stimulus properties, including the predictability of the frequency and timing of tones (Bäss et al, 2008; Knolle et al, 2013a) or manipulations of voice identity (Johnson et al, 2021), voice quality and timing in speech (Aliu et al, 2009; Behroozmand & Larson, 2011). In a study comparing different utterances of the same vowel, self- or externally generated, Niziolek and colleagues (2013) observed greater suppression when the utterance showed formant ratios more prototypical for the individual speaker.…”

Variability in white matter structure relates to hallucination proneness

“…Within the triple-network model, information transfer from inferior frontal hypersalient and central executive engagement resulting in activation of the temporal speech regions may correspond structurally with the anterior AF segment. Indeed, the right IFG has shown increased activity in monitoring unexpected features of auditory and voice feedback 94,95 . Further, the HP-related increases in the FA of the right posterior AF reported here suggest a contribution of structural connections to a sense of agency over external stimuli.…”