New methods for studying hallucinated 'voices' in schizophrenia

Area of Science:

• Neuroscience
• Psychiatry
• Computational modeling

Background:

• Auditory hallucinations ('voices') are a core symptom of schizophrenia, yet their underlying neural mechanisms remain unclear.
• Current understanding suggests a potential link between altered speech perception and the generation of these hallucinations.

Purpose of the Study:

• To investigate the hypothesis that schizophrenic hallucinations arise from pathological alterations in speech perception networks.
• To simulate and experimentally validate the role of speech perception network dysfunction in auditory hallucinations.

Main Methods:

• Computer simulations of neural networks modeling narrative speech perception, incorporating simulated network disconnections and neuromodulatory disturbances.
• Empirical testing of schizophrenic patients using a masked speech tracking (MST) task to assess speech perception abilities under noisy conditions.

Main Results:

• Simulations successfully generated 'hallucinated speech' (percepts without auditory input) and speech perception deficits.
• Schizophrenic patients with hallucinations exhibited significant impairments in speech perception and showed experimentally induced perceptual illusions compared to controls.
• These deficits and illusions in patients mirrored findings from the computational models.

Conclusions:

• The study provides strong support for the hypothesis that auditory hallucinations in schizophrenia are generated by aberrant speech perception networks.
• Findings suggest that 'voices' may be internally generated percepts due to dysfunction within the brain's auditory processing system.