Emotional self–other voice processing in schizophrenia and its relationship with hallucinations: ERP evidence

Abstract

Abnormalities in self-other voice processing have been observed in schizophrenia, and may underlie the experience of hallucinations. More recent studies demonstrated that these impairments are enhanced for speech stimuli with negative content. Nonetheless, few studies probed the temporal dynamics of self versus nonself speech processing in schizophrenia and, particularly, the impact of semantic valence on self-other voice discrimination. In the current study, we examined these questions, and additionally probed whether impairments in these processes are associated with the experience of hallucinations. Fifteen schizophrenia patients and 16 healthy controls listened to 420 prerecorded adjectives differing in voice identity (self-generated [SGS] versus nonself speech [NSS]) and semantic valence (neutral, positive, and negative), while EEG data were recorded. The N1, P2, and late positive potential (LPP) ERP components were analyzed. ERP results revealed group differences in the interaction between voice identity and valence in the P2 and LPP components. Specifically, LPP amplitude was reduced in patients compared with healthy subjects for SGS and NSS with negative content. Further, auditory hallucinations severity was significantly predicted by LPP amplitude: the higher the SAPS "voices conversing" score, the larger the difference in LPP amplitude between negative and positive NSS. The absence of group differences in the N1 suggests that self-other voice processing abnormalities in schizophrenia are not primarily driven by disrupted sensory processing of voice acoustic information. The association between LPP amplitude and hallucination severity suggests that auditory hallucinations are associated with enhanced sustained attention to negative cues conveyed by a nonself voice.

Auditory predictions and prediction errors in response to self-initiated vowels

“…Interestingly, a recent study (Pinheiro et al, 2018) testing non-clinical voice hearers using a similar setup as the first experiment in the current study, also using natural vowel sounds, showed that the N1-supression effect is reversed in non-clinical voice hearers with high symptom scores compared to those with low symptom scores whereas the P2-supression effect is maintained in both groups. This is in accordance with findings in schizophrenia patients (Ford, et al, 2014) using a similar paradigm, which indicates that alterations in generating motor-toauditory predictions might be linked to developing auditory hallucinations (Brebion et al, 2016;Pinheiro et al, 2017).…”

Voice-selective prediction alterations in nonclinical voice hearers

“…Thus, a prediction error may arise from the comparison of a less specific/accurate prediction with the available sensory feedback. A less specific prediction may imply altered self-monitoring of speech, which has been consistently associated with AVH 34 , 36 , 37 , 59 – 62 .…”

“…Before Experiment 2, a voice recording session took place: participants were instructed to repeatedly vocalize the syllable “ah”. Recordings were made with an Edirol R-09 recorder and CS-15 cardioid-type stereo microphone 37 , 45 . After the recording, the best voice sample of the vowel /a/ from each participant (i.e., constant prosody; maximum duration of 300 ms) was selected.…”

“…A substantial body of evidence shows that a failure to distinguish between internally and externally generated sensory signals (e.g., one’s own voice vs . somebody else’s voice) may underlie the experience of AVH 34 , 36 , 37 . This is reflected in a reduced N1 suppression effect when listening to real-time feedback of one’s own voice 6 , 11 , 38 or in button-press tasks (contrasting self-initiation of a sound with passive exposure to the same sound) 13 .…”

Temporal Features of Psychological and Physical Self-Representation: An ERP Study

“…With the advantages of high temporal resolution and direct measure of neural activity, event-related potential (ERP) is an ideal methodology for exploring the dynamical temporal features of cognitive processing (Graux et al., 2013, 2015; Pinheiro et al., 2016, 2017). A growing number of ERP studies have provided evidences of the self-relevant effect.…”