The purpose of my lecture is to review the history of neuropsychology in Japan and explore its future. First, I reviewed my own work, which developed from single-case studies to group studies. Second, I compared the titles of the presentations at Japan Society for Higher Brain Dysfunction of this year and those of 13 years ago. More studies on amnesia were reported this year than 13 years ago, whereas less studies on aphasia were reported this year. In addition, it was predicted that neuropsychology will consist of two aspects: clinical diagnosis and basic neuroscience. Third, I reviewed the contents of the Educational Lectures of this conference. Finally, I concluded that we need to train medical doctors specialized for higher brain dysfunctions. Furthermore, we need to develop medical teams which consists of MDs, STs, PTs, OTs, psychologists, etc., in as many hospitals as possible. What I need to do in the future is to conduct more researches on symptomatologically immature areas such as demantia and cognitive disorders in Parkinson's disease. What we all need to do together is to enrich medical system for patients with higher brain dysfunction.

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[in Japanese]

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Studies in human and other primates reveal that the amygdala, orbitofrontal and ventromedial frontal cortices, and cerebral cortex in and near the superior temporal sulcus (STS) region are important components of facial cognition. We investigated neural mechanisms that were involved in recognizing facial expressions in patients with Parkinson's disease (PD) by visual event-related potentials and the dipole-tracing method. Our result showed that dysfunction of the amygdala in patient with PD changes the neural substrates that are normally used to recognize facial expression. Instead of amygdala, STS region in patients with PD were predominantly involved in response to fearful facial expression, as compared with normal subjects. The impairment of social cognition which include facial expression recognition is important as new mental change in association with PD.

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We discussed music processing in the brain, especially the cognitive function of amygdala during listening to music. The amusical cases in the reported literatures revealed the double dissociation between the perception and emotional responses of music. This suggested that these two cognitive functions were based on independent neural processing. An activation study using positron emission tomography (PET) for the emotional responses to music failed to show the activation of amygdala during listening to dissonant chords. We performed a PET activation study for the recognition of the timber. The subjects were required to detect the change of instrumentals or to triplets. During the former task, bilateral amygdala, parahippocampal gyri, cyngulate giri, anterior temporal regions were significantly activated. We tried to interpret the functional significance of amygdala during timber recognition from the view-point of evolution and emotion. By using music, we can obtain new findings of the neural processing of emotion.

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In this review article, I will focus on three fundamental issues concerning language processing in the human brain, and update recent advances made by brain mapping studies of language. First, I will provide the first experimental evidence that the neural basis of sentence comprehension is indeed specialized. Specifically, our recent functional magnetic resonance imaging (fMRI) and transcranial magnetic stimulation (TMS) studies have proved that the left dorsal inferior frontal gyrus (IFG) is more specialized in the syntactic processes of sentence comprehension than other general cognitive processes such as short-term memory. These results suggest that the left IFG plays an essential role in grammatical processing, which is thus referred to as the grammar center. Second, we have recently discovered that the activation increases of the left IFG were positively correlated with individual performance improvements during the early phase of second language (L2) acquisition. These results further suggest that the cortical plasticity for L2 acquisition specifically involves the grammar center. Third, we have established that a new link between orthography and phonology is formed when adults learn letters, which is selectively based on the plasticity of a letter center involving the left posterior inferior temporal gyrus (PITG). The current direction of research in systems neuroscience contributes to clarifying that the specific cortical regions subserve uniquely human functions during language processing.

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The purpose of this study was to define the different roles exercised by consonants and formant transition in recognition of speech sounds. Three sets of stimulus sounds were generated by computer from natural Japanese monosyllables. The stimuli of the first set had both natural consonants and natural formant transitions. The stimuli of the second set had natural consonants but no transition. The stimuli of the third set had natural formant transitions but no consonants. The stimuli were recorded on compact disc and presented binaurally. The subjects repeated the syllables. The subjects were 31 aphasics who had lesions in the left hemisphere and 18 normal geriatrics. It was revealed that a correct response rate at repetition could indicate performance of speech sound recognition, because the longer the duration of the consonants or transitions of the syllables were, the higher were the correct response rates of the aphasic patients. The consonant was the cue of recognition for some Japanese syllables (sa, za, ma, ba) ; however, both the consonant and transition were indispensable to recognize other syllables (pa, ta, ka, da, ga, na, la). Information on both consonant and transition was necessary to identify the point of articulation. Information concerning the consonant was required to identify the manner of articulation as well as nasality. Information on the consonant or transition was necessary for identification of vocality. The findings indicated that lesions of the left inferior supramarginal gyrus are responsible for disturbance of recognition of speech sounds. Correct and prompt recognition of human speech seemed to be realized when features are extraced initially from the consonant (first stage), then from the transition (second stage).

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In this study we evaluated the ability of elderly people to comprehend Japanese grammar in order to investigate the influence of aging and cognitive impairment on language ability. The cognitive ability of 55 participants with a mean age of 78.4 years was evaluated with a Japanese version of the Mini-Mental State (MMS) test. Their grammatical ability was evaluated using a J.COSS test (JWU's, Japanese Test for Comprehension of Syntax and Semantics). The results revealed that the older group (75-99 years) demonstrated more cognitive impairment and grammatical errors than the younger group (60-74 years). In accordance with the MMS test norm for cognitive disorders (a score of 23 or less), most of the cognitive impairment group was able to understand a two-item combination sentence; however, they had difficulty with comprehension of particles and conjunctions. Moreover, comprehension of complex-syntax-structured sentences was influenced by both aging and cognitive impairment. Although previous studies have not shown any influence of age-related decline in lexical knowledge on language ability, the present study revealed a deterioration in grammatical knowledge influenced by aging and cognitive impairment in old age. Because of this evidence that age-related decline in language processing is in some cases due to an age-related decline in the working memory, the findings suggest that a grammatical deficit with age may be associated with frontal lobe function.

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We experienced a case of aphasia whose language abilities showed good recovery after introduction of nasal continuous positive airway pressure (nCPAP) for treatment of obstructive sleep apnea hypopnea syndrome (OSAHS). The subject was a 43-year-old right-handed male university graduate. He developed a cerebral hemorrhage after a shunt operation for cerebral vein sinus thrombosis in March 1999, and right hemiplegia and severe aphasia remained. He was admitted to Edogawa Hospital eight months after the onset, and started undergoing intensive therapy for aphasia. He experienced sleep apnea and snoring before the onset, and was diagnosed by polysomnography as having moderate OSAHS. After two years of language training for aphasia, we introduced nCPAP to the subject. The standard language test of aphasia (SLTA) revealed remarkable improvement, especially in the subtests of speech that had showed slow recovery, compared with performances before the introduction of nCPAP. In addition, fluency of conversation in daily life also improved, resulting in much easier communication. These results suggest that ventilation with nCPAP is effective for recovery from aphasia.

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