Reduced auditory cortex activation during speech perception in patients with schizophrenia

 

There is no evidence that auditory verbal hallucinations impact speech perception at the level of words or sentences, or the perception of unintelligible speech. Regardless of the presence of auditory verbal hallucinations, schizophrenia patients show reduced auditory cortex activation during speech perception [1].

The hearing of ‘voices’ (auditory verbal hallucinations) by schizophrenic patients has been linked to reduced activation in the left auditory cortex during the hearing of real auditory stimuli such as tones and speech [2,3]. Soler-Vidal (University of Barcelona, Spain) and colleagues conducted a functional neuroimaging study to examine brain activity in response to spoken speech and its association with the presence of auditory verbal hallucinations in patients with schizophrenia [1].

Included were 30 patients who met the DSM-5 criteria for schizophrenia or schizoaffective disorder with frequent auditory verbal hallucinations (at least 1 per day) and 37 patients who met the same DSM-5 criteria but who did not experience any auditory hallucinations. A control group of 31 healthy individuals was selected and all 3 groups were matched for age, sex, and estimated IQ. While performing an auditory speech perception task (i.e. spoken words, spoken sentences and spoken unintelligible reversed speech), participants underwent functional (f)MRI. They also completed a questionnaire. This resulted in available data from 46 patients (23 with auditory verbal hallucinations and 23 without) and 25 participants from the control group.

Speech perception in the form of words, sentences, or reversed speech elicited activation of the bilateral temporal cortex, the inferior and lateral prefrontal cortex, the inferior parietal cortex, and the supplementary motor area. During word perception, no group differences were observed. During sentence perception and reversed speech perception, hypoactivation of the left primary auditory cortex was observed in the schizophrenia group. For sentence perception, patients failed to deactivate the left interior parietal cortex and the praecuneus, relative to the control group. No differences were found between schizophrenia patients with and without auditory verbal hallucinations [3].

In conclusion, no evidence was found for the impact of auditory verbal hallucinations on speech perception. The failure to deactivate the left interior parietal cortex and praecuneus might reflect a dysfunction of the default mode network, which has often been reported in schizophrenia [4].

 

1. Soler-Vidal J, et al. Brain correlates of speech perception in schizophrenia patients with and without auditory verbal hallucinations. P.714. ECNP Congress 2020.
2. Ford J, et al. Schizophr Bull. 2009;35:58-66.
3. Plaze M, et al. Schizophr Res. 2006;87:109-115.
4. Pomarol-Clotet E, et al. Med. 2008;38(8):1185-1193.

Posted on 2 November 20205 August 2021