Functional Neuroimaging of Auditory Linguistic and Vocal Affective Processing for Diagnosis and Treatment of Psychiatric Disorders

Abstract

To clarify the neural basis of distorted thinking, such as hallucination and delusion, recent functional neuroimaging studies demonstrated the abnormality of linguistic and emotional brain functions in psychiatric disorders. In this article, we aimed to discuss the practicability of functional neuroimaging as a clinical application in neuropsychiatry. First, we explained the fundamental principle of functional MRI. Next, we summarized our recent findings from the application of functional MRI in relation to auditory linguistic brain function and voice-specific brain function. Some of our previous clinical functional neuroimaging studies demonstrated 1) a reduction of left-hemispheric linguistic brain function in schizophrenia, 2) right-lateralized hypoactivation of voice-specific brain response at the superior temporal gyrus in schizophrenia, 3) functional abnormality of social brain regions while subjects were judging auditory attractiveness, 4) a reduction of left lateral frontal function in depressive state, as well as loss of interest and pleasure. These previous findings have pointed out the significance of investigating linguistic and emotional brain functions during the clinical assessment of neuropsychiatry patients, such as those with schizophrenia and depression. In the recognition of non-verbal auditory affective contents, our previous findings revealed cross-cultural differences, thereby suggesting the importance of considering the influence of cross-cultural differences in the clinical evaluation of the affective state. Further, our recent findings also demonstrated the importance of functional neuroimaging for evaluating the pharmacological effect on emotional brain regions by psychotropic drugs, such as by modafinil and bupropion.In addition, our results also alluded to the importance of evaluating linguistic brain function by functional MRI to examine the effect of transcranial direct-current stimulation.