Default mode network alterations underlie auditory verbal hallucinations in schizophrenia

Area of Science:

• Neuroscience
• Psychiatry
• Brain Imaging

Background:

• Default Mode Network (DMN) alterations are known in schizophrenia (SZ).
• Less is understood about DMN changes in specific schizophrenia sub-phenotypes, particularly those with auditory verbal hallucinations (AVH).

Purpose of the Study:

• To investigate and compare DMN features in schizophrenia patients with and without AVH against healthy controls.
• To explore the neural underpinnings of AVH within the DMN.

Main Methods:

• A pilot study involving three groups: AVH-SZ patients, non-hallucinating SZ patients (nAVH-SZ), and age-matched healthy controls (HC), each with 17 participants.
• Analysis of DMN spatial patterns and spectral activity using normalized fractional Amplitude of Low-Frequency Fluctuations (fALFF).

Main Results:

• DMN spatial patterns were similar between nAVH-SZ and HC groups.
• AVH-SZ patients exhibited altered DMN activity, particularly in the left Angular Gyrus (lAG), compared to nAVH-SZ and HC groups.
• Altered spectral activity in lower-frequency bands (0.017-0.04 Hz) was observed in AVH-SZ patients.
• Correlations between delusional scores (PANSS-P1) and slow fALFF bands were found in SZ groups.
• In AVH-SZ, hallucination scores (PANSS-P3) correlated with fALFF in specific slow bands (Slow-5, Slow-4 positive; Slow-3 negative) within the lAG region.

Conclusions:

• The left Angular Gyrus (lAG) plays a crucial role in auditory verbal hallucinations in schizophrenia.
• The lAG's connectivity to auditory and frontal language centers highlights its importance in auditory processing and monitoring deficits in AVH-SZ.
• fALFF analysis reveals distinct DMN spectral activity patterns associated with AVH in schizophrenia.