Functional connectivity of left Heschl's gyrus in vulnerability to auditory hallucinations in schizophrenia

Schizophrenia is a heterogeneous disorder that may consist of multiple etiologies and disease processes. Auditory hallucinations (AH), which are common and often disabling, represent a narrower and more basic dimension of psychosis than schizophrenia. Previous studies suggest that abnormal primary auditory cortex activity is associated with AH pathogenesis. We thus investigated functional connectivity, using a seed in primary auditory cortex, in schizophrenia patients with and without AH and healthy controls, to examine neural circuit abnormalities associated more specifically with AH than the myriad other symptoms that comprise schizophrenia.

Using resting-state fMRI (rsfMRI), we investigated functional connectivity of the primary auditory cortex, located on Heschl's gyrus, in schizophrenia spectrum patients with AH. Participants were patients with schizophrenia, schizoaffective disorder, or schizophreniform disorder with lifetime AH (n=27); patients with the same diagnoses but no lifetime AH (n=14); and healthy controls (n=28).

Patients with AH vulnerability showed increased left Heschl's gyrus functional connectivity with left frontoparietal regions and decreased functional connectivity with right hippocampal formation and mediodorsal thalamus compared to patients without lifetime AH. Furthermore, among AH patients, left Heschl's gyrus functional connectivity covaried positively with AH severity in left inferior frontal gyrus (Broca's area), left lateral STG, right pre- and postcentral gyri, cingulate cortex, and orbitofrontal cortex. There were no differences between patients with and without lifetime AH in right Heschl's gyrus seeded functional connectivity.

Abnormal interactions between left Heschl's gyrus and regions involved in speech/language, memory, and the monitoring of self-generated events may contribute to AH vulnerability.