抄録
There is evidence for sensory and cognitive impairments at multiple levels in schizophrenia, which may be related to the clinical symptoms of the condition. Inner speech involves both auditory and language systems and dysfunction of inner speech and may be associated with auditory hallucinations in schizophrenia. We used functional magnetic resonance imaging to examine this association by measuring brain activation in 23 patients with schizophrenia and 23 healthy control individuals. The participants performed an auditory verbal working memory task that required inner speech in the form of subvocal rehearsal. The control participants showed prominent activation in the inferior frontal cortex (IFC), premotor cortex (PMC), superior temporal cortex (STC), and lateral parietal cortex (LPC) bilaterally, throughout the task. In contrast, patients with schizophrenia showed significant activation in STC bilaterally during encoding phase and in the IFC, PMC, STC, and LPC bilaterally during the recognition phase. A comparison between groups showed that controls had greater activation during rehearsal in the IFC, LPC, and PMC bilaterally than patients with schizophrenia. In the region-of-interest analysis, we observed a significant negative correlation between right PMC activation and Auditory Hallucination Rating Scale scores as well as the hallucination item in the Positive and Negative Syndrome Scale. These observations indicate that inner speech is impaired in schizophrenia and that the severity of auditory hallucinations is associated with abnormal activation in the right PMC during inner speech.
