Emergence Of Auditory Verbal Hallucinations Research Articles

The moderating effect of cognitive impairment on the relationship between inner speech and auditory verbal hallucinations among chronic patients with schizophrenia

BackgroundEven though there is an increasing amount of evidence from behavioral and neuroimaging studies to suggest that pathological inner speech plays a role in the emergence of auditory verbal hallucinations (AVH), studies investigating the mechanisms underlying this relationship are rather scarce. Examining moderators might inform the development of new treatment options for AVH. We sought to extend the existing knowledge by testing the moderating role of cognitive impairment in the association between inner speech and hallucinations in a sample of Lebanese patients with schizophrenia.MethodsA cross-sectional study was conducted from May till August 2022, enrolling 189 chronic patients.ResultsModeration analysis revealed that, after controlling for delusions, the interaction of experiencing voices of other people in inner speech by cognitive performance was significantly associated with AVH. In people having low (Beta = 0.69; t = 5.048; p < .001) and moderate (Beta = 0.45; t = 4.096; p < .001) cognitive performance, the presence of voices of other people in inner speech was significantly associated with more hallucinations. This association was not significant in patients with high cognitive function (Beta = 0.21; t = 1.417; p = .158).ConclusionThis preliminarily study suggests that interventions aiming at improving cognitive performance may also have a beneficial effect in reducing hallucinations in schizophrenia.

Aberrant Perceptual Judgments on Speech-Relevant Acoustic Features in Hallucination-Prone Individuals

Abstract Hallucinations constitute an intriguing model of how percepts are generated and how perception can fail. Here, we investigate the hypothesis that an altered perceptual weighting of the spectro-temporal modulations that characterize speech contributes to the emergence of auditory verbal hallucinations. Healthy human adults (N = 168) varying in their predisposition to hallucinations had to choose the “more speech-like” of two presented ambiguous sound textures and give a confidence judgment. Using psychophysical reverse correlation, we quantified the contribution of different acoustic features to a listener’s perceptual decisions. Higher hallucination proneness covaried with perceptual down-weighting of speech-typical, low-frequency acoustic energy and prioritizing of high frequencies. Remarkably, higher confidence judgments in single trials depended not only on acoustic evidence but also on an individual’s hallucination proneness and schizotypy score. In line with an account of altered perceptual priors and differential weighting of sensory evidence, these results show that hallucination-prone individuals exhibit qualitative and quantitative changes in their perception of the modulations typical for speech.

Alterations in interhemispheric gamma-band connectivity are related to the emergence of auditory verbal hallucinations in healthy subjects during NMDA-receptor blockade.

Auditory verbal hallucinations (AVH) are a common positive symptom of schizophrenia. Excitatory-to-inhibitory (E/I) imbalance related to disturbed N-methyl-D-aspartate receptor (NMDAR) functioning has been suggested as a possible mechanism underlying altered connectivity and AVH in schizophrenia. The current study examined the effects of ketamine, a NMDAR antagonist, on glutamate-related mechanisms underlying interhemispheric gamma-band connectivity, conscious auditory perception during dichotic listening (DL), and the emergence of auditory verbal distortions and hallucinations (AVD/AVH) in healthy volunteers. In a single-blind, pseudo-randomized, placebo-controlled crossover design, nineteen male, right-handed volunteers were measured using 64 channel electroencephalography (EEG). Psychopathology was assessed with the PANSS interview and the 5D-ASC questionnaire, including a subscale to detect auditory alterations with regard to AVD/AVH (AUA-AVD/AVH). Interhemispheric connectivity analysis was performed using eLORETA source estimation and lagged phase synchronization (LPS) in the gamma-band range (30-100 Hz). Ketamine induced positive symptoms such as hallucinations in a subgroup of healthy subjects. In addition, interhemispheric gamma-band connectivity was found to be altered under ketamine compared to placebo, and subjects with AUA-AVD/AVH under ketamine showed significantly higher interhemispheric gamma-band connectivity than subjects without AUA-AVD/AVH. These findings demonstrate a relationship between NMDAR functioning, interhemispheric connectivity in the gamma-band frequency range between bilateral auditory cortices and the emergence of AVD/AVH in healthy subjects. The result is in accordance with the interhemispheric miscommunication hypothesis of AVH and argues for a possible role of glutamate in AVH in schizophrenia.

Reduced Neuronal Activity in Language-Related Regions After Transcranial Magnetic Stimulation Therapy for Auditory Verbal Hallucinations

Transcranial magnetic stimulation (TMS) is a novel therapeutic approach, used in patients with pharmacoresistant auditory verbal hallucinations (AVH). To investigate the neurobiological effects of TMS on AVH, we measured cerebral blood flow with pseudo-continuous magnetic resonance-arterial spin labeling 20 ± 6 hours before and after TMS treatment. Thirty patients with schizophrenia or schizoaffective disorder were investigated. Fifteen patients received a 10-day TMS treatment to the left temporoparietal cortex, and 15 received the standard treatment. The stimulation location was chosen according to an individually determined language region determined by a functional magnetic resonance imaging language paradigm, which identified the sensorimotor language area, area Spt (sylvian parietotemporal), as the target region. TMS-treated patients showed positive clinical effects, which were indicated by a reduction in AVH scores (p ≤ .001). Cerebral blood flow was significantly decreased in the primary auditory cortex (p ≤ .001), left Broca's area (p ≤ .001), and cingulate gyrus (p ≤ .001). In control subjects, neither positive clinical effects nor cerebral blood flow decreases were detected. The decrease in cerebral blood flow in the primary auditory cortex correlated with the decrease in AVH scores (p ≤ .001). TMS reverses hyperactivity of language regions involved in the emergence of AVH. Area Spt acts as a gateway to the hallucination-generating cerebral network. Successful therapy corresponded to decreased cerebral blood flow in the primary auditory cortex, supporting its crucial role in triggering AVH and contributing to the physical quality of the false perceptions.

Cortical Activations During Auditory Verbal Hallucinations in Schizophrenia: A Coordinate-Based Meta-Analysis

Auditory verbal hallucinations (AVHs) constitute severe, incapacitating symptoms of schizophrenia. Despite increasing interest in the functional exploration of AVHs, the available findings remain difficult to integrate because of their considerable variability. The authors' aim was to perform a robust quantitative review of existing functional data in order to elucidate consistent patterns observed during the emergence of AVHs and to orient new pathophysiological models of hallucinations. Ten positron emission tomography or functional magnetic resonance imaging studies were selected for the meta-analysis after systematic review. A total of 68 patients with schizophrenia spectrum disorders experiencing AVHs during scanning were included. According to a random-effects activation likelihood estimation algorithm, stereotaxic coordinates of 129 foci, reported as significant in the source studies, were extracted and computed to estimate the brain locations most consistently associated with AVHs across studies (cluster-extent threshold: 200 mm³). Patients experiencing AVHs demonstrated significantly increased activation likelihoods in a bilateral neural network, including the Broca's area (activation likelihood estimation=1.84×10⁻³), anterior insula (1.78×10⁻³), precentral gyrus (1.46×10⁻³), frontal operculum (1.29×10⁻³), middle and superior temporal gyri (1.59×10⁻³), inferior parietal lobule (1.33×10⁻³), and hippocampus/parahippocampal region (1.90×10⁻³). This meta-analysis demonstrated that experiencing AVHs is associated with increased activity in fronto-temporal areas involved in speech generation and speech perception, but also within the medial temporal lobe, a structure notably involved in verbal memory. Such findings support a model for AVHs in which aberrant cortical activations emerge within a distributed network involved at different levels of complexity in the brain architecture. Critical future directions are considered.