Abnormal connectivity and activation during audiovisual speech perception in schizophrenia

Area of Science:

• Neuroscience
• Psychiatry
• Cognitive Science

Background:

• Effective face-to-face communication relies on integrating vocal and facial cues during speech perception.
• Previous research indicates behavioral deficits in audiovisual speech perception in schizophrenia.
• The underlying neurophysiological mechanisms of these deficits in schizophrenia remain unclear.

Purpose of the Study:

• To investigate neural activity and connectivity in the auditory cortex during audiovisual speech perception in schizophrenia.
• To compare the subadditive response and functional connectivity between schizophrenia patients and healthy controls.

Main Methods:

• Magnetoencephalography (MEG) was used to record event-related fields.
• Auditory (voice), visual (face), and audiovisual (voice-face) stimuli were presented to 23 schizophrenia patients and 22 healthy controls.
• Analysis focused on subadditive responses and functional connectivity, particularly from the left posterior ramus of the lateral sulcus.

Main Results:

• Healthy controls exhibited a subadditive N1m effect (audiovisual response < sum of auditory and visual responses) in the left hemisphere.
• Schizophrenia patients lacked this subadditive response, indicating impaired audiovisual integration.
• Weaker functional connectivity was found in schizophrenia patients from the left auditory cortex to the right fusiform gyrus, correlating with negative symptom severity.

Conclusions:

• Schizophrenia is associated with abnormal connectivity between speech- and face-processing cortical areas.
• Deficits in audiovisual speech integration, characterized by aberrant subadditive responses and weakened connectivity, may underlie social communication impairments in schizophrenia.