Schizophrenia patients show sound localization and discrimination deficits
MedWire News: Patients with schizophrenia show impairments in both localization and spatial discrimination of sounds, say researchers.
"Schizophrenia is a severe neuropsychiatric illness associated with widespread deficits in neurocognition," explain Megan Perrin (Nathan Kline Institute for Psychiatric Research, New York, USA) and colleagues.
They add that although such deficits "have been studied primarily in relationship to higher cognitive function, increasing evidence implicates dysfunction within primary sensory cortex."
To investigate whether schizophrenia patients exhibit deficits in the localization and discrimination of free-field sound, the team enrolled 21 patients with the mental health disorder (90.5% men) and 20 mentally healthy controls (75.0% men) without hearing impairments.
For the sound localization test, the participants were asked to listen to 20 tones generated randomly from seven speakers concavely arranged within a room with 30° separation, and identify the speaker from which the sound came.
To test the participant's spatial discrimination of sound, two tones were sequentially presented 150 ms apart from either the same or different speakers, and the participants were asked to identify the speaker or speakers from which the tones came, while ignoring the relative position of the tones.
The researchers found that patients with schizophrenia performed significantly worse than controls on the sound localization task, and exhibited greater overall response variability, particularly in the right hemifield.
Schizophrenia patients also performed significantly worse on the spatial discrimination task than controls.
In schizophrenia patients, reduced accuracy on both tasks in the right hemifield was associated with greater symptom severity, as assessed using the Positive and Negative Symptoms Scale.
The team also notes that greater accuracy in the left hemifield on the sound localization task was associated with greater hallucination severity, but no significant association was found in the spatial discrimination task.
Perrin and team conclude in the journal Schizophrenia Research: "The present study demonstrates impaired spatial localization ability in schizophrenia in a pattern consistent with right or bilateral primary cortex dysfunction."
They add: "These findings support generalized models of cognitive dysfunction in schizophrenia, and suggest need for further studies investigating the relationship of sensory cortical dysfunction to symptoms and deficits of schizophrenia."
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By Mark Cowen