Schizophrenia Bulletin: Diminished Auditory Cortex Dynamic Range and Its Clinical Correlates in First Episode Psychosis

Despite the prevailing focus on executive functioning impairments as primary contributors to clinical outcomes in individuals with psychosis, the contribution of sensory disruptions to disease morbidity in psychosis is receiving increasing attention among scientists who study schizophrenia and other psychotic disorders. Reductions in neurophysiological markers of both auditory and visual early perceptual processing suggest a faulty stimulus registration mechanism in schizophrenia that, in turn, compounds higher-order cognitive deficits. In the auditory domain, an inability to perceive variations in acoustic features (e.g., pitch and intensity) has been associated with impaired emotional processing and functional decline in schizophrenia.

“While auditory sensory deficits have been investigated in schizophrenia, little work has been done to understand how the brain adapts to changes in the auditory environment, particularly during early stages of the illness. Given the complexity of stimuli encountered in real-world settings, deficits in this adaptive process can have profound impacts on social and occupational functioning,” said Alfredo Sklar, MD, PhD (Assistant Professor of Psychiatry), first author of a study recently published in Schizophrenia Bulletin. 

Investigators including Dr. Sklar, Brian Coffman, PhD (Research Assistant Professor of Psychiatry), and Dean Salisbury, PhD (Professor of Psychiatry), examined neurophysiological responses to pure tones among 35 individuals with schizophrenia following their first psychotic episode, to assess auditory cortex dynamic range and its potential clinical consequences at the onset of schizophrenia. The scientists recorded magnetoencephalography (MEG) from study participants (additionally including 40 unaffected comparison participants) during binaural presentation of tones at three intensities. 

The paper published in Schizophrenia Bulletin is the first to localize the cortical sources of this sensory activity using MEG in individuals with early symptoms of schizophrenia, and first to demonstrate a blunted scaling of this response to stimulus intensity.

“When individuals first experience psychosis symptoms, their auditory system does not track sound intensity well, so everything may seem muted. Further, the subtle changes in inflection that convey emotional emphasis are likely not well perceived. This means that these individuals have difficulty comprehending both verbal and non-verbal information in language, which will make effective real-world functioning much harder. Our task now is to discover what kinds of novel interventions might improve this sensory deficit,” said Dr. Salisbury, senior author of the study.

Diminished auditory cortex dynamic range and its clinical correlates in first episode psychosis
Sklar AL, Ren X, Chlpka L, Curtis M, Coffman BA, Salisbury DF. 
Schizophrenia Bulletin, Volume 49, Issue 3, May 2023, Pages 679–687, https://doi.org/10.1093/schbul/sbac208