Abstract
People with schizophrenia exhibit impairments in target-speech recognition (TSR) against multiple-talker-induced informational speech masking. Up to date, the underlying neural mechanisms and its relationships with psychotic symptoms remain largely unknown. This study aimed to investigate whether the schizophrenia-associated TSR impairment contribute to certain psychotic symptoms by sharing underlying alternations in cortical gray-matter volume (GMV) with the psychotic symptoms. Participants with schizophrenia (N = 34) and their matched healthy controls (N = 29) were tested for TSR against a two-talker-speech masker. Psychotic symptoms of participants with schizophrenia were evaluated using the Positive and Negative Syndrome Scale. The regional GMV across various cortical regions was assessed using the voxel-based morphometry. The results of partial-correlation and mediation analyses showed that in participants with schizophrenia, the TSR was negatively correlated with the delusion severity, but positively with the GMV in the bilateral superior/middle temporal cortex, bilateral insular, left medial orbital frontal gyrus, left Rolandic operculum, left mid-cingulate cortex, left posterior fusiform, and left cerebellum. Moreover, the association between GMV and delusion was based on the mediating role played by the TSR performance. Thus, in people with schizophrenia, both delusions and the augmented vulnerability of TSR to informational masking are associated with each other and share the underlying cortical GMV reduction, suggesting that the origin of delusion in schizophrenia may be related to disorganized or limited informational processing (e.g., the incapability of adequately filtering information from multiple sources at the perceptual level). The TSR impairment can be a potential marker for predicting delusion severity.
Highlights
Impairments in speech and thought processes have been considered as critical characteristics in people with schizophrenia [1,2,3,4]
Since impaired inhibitory mechanisms at the neurobiological level in people with schizophrenia are associated with certain psychotic symptoms reflecting the incapability of adequately processing multiple inputs at the perceptual level [8,9,10], it is of importance to know whether deficits of perceptual/cognitive processes and certain symptoms in people with schizophrenia share the same or similar underlying neural substrates associated with impaired inhibitory processing
This study discovers that the delusion symptom severity is associated with the reduced target-speech recognition (TSR) against informational masking, and the TSR mediates the association between the delusion symptom and the reduced gray-matter volume (GMV) in somce brain regions known to be normally involved in processing of masked speech [11,12,13,14,15,16,17,18, 20, 21] and cognitive controls [51, 52]
Summary
Impairments in speech and thought processes have been considered as critical characteristics in people with schizophrenia [1,2,3,4]. It has been suggested that investigation of the relationship between deficits of perceptual/cognitive processes and typical symptoms of schizophrenia is important for understanding the nature of this disorder [5,6,7]. Since impaired inhibitory mechanisms at the neurobiological level in people with schizophrenia are associated with certain psychotic symptoms reflecting the incapability of adequately processing multiple inputs at the perceptual level [8,9,10], it is of importance to know whether deficits of perceptual/cognitive processes and certain symptoms in people with schizophrenia share the same or similar underlying neural substrates associated with impaired inhibitory processing. One research strategy for this issue is to investigate whether the vulnerability of TSR to informational masking and certain psychotic symptoms share the same or similar underlying neural substrates
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