Synch before you speak: auditory hallucinations in schizophrenia.

Area of Science:

• Neuroscience
• Psychiatry
• Cognitive Science

Background:

• The forward model is a neural mechanism that predicts sensory consequences of self-generated actions.
• This model may dampen sensory feedback, reducing the impact of self-generated sensations.
• Deficits in this mechanism are hypothesized to underlie positive symptoms in schizophrenia, such as auditory hallucinations.

Purpose of the Study:

• To investigate the relationship between neural synchrony preceding speech and auditory sensory suppression.
• To compare neural synchrony in schizophrenia patients and healthy individuals.
• To examine the correlation between neural synchrony and auditory hallucination severity.

Main Methods:

• EEG phase coherence was used to measure neural synchrony preceding speech.
• Auditory cortical suppression was assessed by comparing N1 event-related potentials during talking versus listening.
• The study included 24 patients with schizophrenia/schizoaffective disorder and 25 healthy controls.

Main Results:

• Healthy subjects exhibited greater prespeech neural synchrony, which correlated with subsequent auditory suppression.
• Schizophrenia patients showed reduced prespeech neural synchrony compared to healthy controls.
• This reduction was more pronounced in patients with severe auditory hallucinations.

Conclusions:

• EEG synchrony preceding speech appears to reflect the functioning of the forward model system.
• A deficient forward model, leading to inadequate dampening of auditory responsiveness to self-generated speech, is implicated in schizophrenia and auditory hallucinations.