[Music Processing in the Brain: Neuropsychological Approach Through Findings of Patients with Amusia]

Less than 100 cases of amusia have been reported. The sites of lesion in these patients have been located in the right, left, and bilateral cerebral hemisphere(s); therefore the lateralization of amusia is not as clear as that of aphasia. Among them, pure amusia, the selective loss of musical ability due to acquired brain damage, was observed only in nine cases. The cases of pure amusia included right superior and middle temporal gyrus lesion involvement. By comparing the lesion sites and symptoms of pure amusia, it might be assumed that the right superior/middle temporal gyrus participates in the perception and expression of melody. In 2011, the selective loss of the experience of musical emotion was termed musical anhedonia by the presenting author. Only four cases of musical anhedonia have been reported, and in those the cortical and subcortical regions of the right temporoparietal area were commonly damaged. It was supposed that musical anhedonia was caused by the disconnection between the right auditory association cortices and the insula. Based on the results of the assessment of healthy young participants, there have been many reports of congenital amusia or musical anhedonia by musical psychologists. Further studies are needed in order to determine whether these diseases actually exist.