Hideto Hirasawa

Activation of the visual cortex imaged by 24-channel near-infrared spectroscopy

Near-infrared spectroscopy (NIRS) is a noninvasive technique for continuous monitoring of the amounts of total hemoglobin (total-Hb), oxygenated hemoglobin, (oxy-Hb) and deoxygenated hemoglobin (deoxy-Hb). The purpose of the present study was to demonstrate the utility of NIRS in functional imaging of the human visual cortex. A new NIRS imaging system enabled measurements from 24 scalp locations covering a 9 cm sq area. Topographic images were obtained from interpolations of the concentration changes between measurement points. Five healthy subjects between 25 and 49 years of age were investigated. After a resting baseline period of 50 s, the subjects were exposed to a visual stimulus for 20 s, followed by a 50 s resting period in a dimly lit, sound attenuating room. The visual stimulus was a circular, black and white, alternating checkerboard. In four of five subjects the visual cortex was the most activated area during visual stimulation. This is the first reported use of a NIRS-imaging system for assessing hemodynamic changes in the human visual cortex. The typical hemodynamic changes expected were observed; the total-Hb and oxy-Hb increased just after the start of stimulation and plateaued after 10 s of the stimulation period.

Suicide and Aging in Japan: An Examination of Treated Elderly Suicide Attempters

Although individuals aged 65 and over accounted for 12% of the total population of Japan in 1990, suicides in this age group consisted of 29% of all suicides. The elderly population of Japan is expected to grow rapidly to 24% of the total population by the year 2020, and suicide prevention for the elderly is an urgent mental health problem. Among a total of 1,216 elderly patients who were admitted to the Department of Psychiatry at Tokyo Metropolitan Geriatric Hospital between April 1980 and March 1990, 50 were hospitalized immediately after suicide attempts in order to study their psychosociomedical problems. Because early diagnosis of depression and initiation of proper treatment are indispensable--even if patients do not show obvious depressive symptoms--those who develop persistent somatization and/or delirium should be considered highly suicidal and given special attention. With the cooperation of mental health professionals, it is necessary to educate general practitioners, the public, and the elderly themselves about characteristics of psychiatric disorders and various problems associated with aging. Further research on other elderly Japanese populations, as well as research that examines suicide completion, is needed to confirm the findings of the present study.

Quantitative EEG correlates of normal aging in the elderly

To clarify the effect of normal aging on the EEG in the elderly, relative EEG power and coherence were studied in 68 elderly subjects (age range 61-90 years) as well as in 20 young subjects (age range 23-38 years). Relative beta power was significantly higher in the elderly subjects, while no significant differences were seen among the elderly groups. Therefore it may be assumed that EEG power in the centrooccipital region among the normal elderly remains almost unchanged. Also, age had no effect on interhemispheric coherence. However, intrahemispheric coherence was found to decrease with age in all bands almost linearly. Thus, intrahemispheric coherence is a more sensitive indicator of normal aging than relative power.

Activation of visual cortex in REM sleep measured by 24‐channel NIRS imaging

To visualize dreaming brain functions we studied hemodynamic changes in the visual cortex during the transition from non‐rapid eye movement (NREM) to rapid eye movement (REM) sleep, using a 24‐channel Near‐Infrared Spectroscopy (NIRS) imaging method. Results were compared to the activation in visual cortex by visual stimulation during wakefulness. Subjects were four healthy males between 25 and 49 years of age. Five all‐night polysomnographic and NIRS recordings were made. Increases in the oxygenated hemoglobin concentration in visual cortex were observed from nine of 14 REM periods. The activated areas were broader during REM sleep than during visual stimulation. These findings suggest that activation of visual cortex in REM sleep might represent dream‐related brain activity.

Suicide in Japan: Present State and Future Directions for Prevention:

There were 23,104 suicides in Japan in 1996, making the suicide rate 18.4 per 100,000, which is not much higher than those of some European countries. This paper focuses on current trends of suicide in Japan. In addition, the problem of suicide among the elderly and some characteristic forms of suicide found in Japan, such as shinju (suicide pact) and inseki-jisatsu (suicide committed in order to take responsibility) are discussed. Future strategies are also proposed for suicide prevention in Japan.

Possible association of missense mutation (Gly63Glu) of the neurotrophin-3 gene with Alzheimer's disease in Japanese

Several lines of evidence have suggested a possible involvement of neurotrophic factors in the pathogenesis of neurodegenerative disease. We examined whether a missense mutation (Gly[-63]Glu) of the neurotrophin-3 (NT-3) gene is associated with Alzheimers disease (AD) in a Japanese sample of 123 patients and 215 controls. We found that homozygotes or heterozygotes for the mutated type (Glu[-63]) were significantly more common among the patients than the controls (P = 0.013, odds ratio 1.77, 95% CI 1.12-2.79). The mutated type was more frequent among the patients than the controls (P = 0.011, odds ratio 1.63, 95%CI 1.11-2.38). This association between NT-3 and AD was more prominent among those who did not carry the epsilon4 allele of the apolipoprotein E gene than those who carried the epsilon4 allele. Our results suggest that the Glu(-63) allele of the NT-3 gene by itself or another mutation nearby which would be in linkage disequilibrium to the mutation is a risk factor for AD.

Cerebral blood volume in the sleep measured by near‐infrared spectroscopy

Abstract We investigated the relationship between hemodynamic changes in the cortex measured by near‐infrared spectroscopy (NIRS) and the polysomnographic changes during sleep. Four healthy male volunteers participated in the study. Near‐infrared spectroscopy measuring and polysomnographic recordings were done simultaneously during sleep. In many case, oxy‐hemoglobin (oxy‐Hb) decreased and deoxy‐hemoglobin (deoxy‐Hb) increased during the transition from wakefulness to sleep, and oxy‐Hb increased toward deep sleep. Oxy‐Hb and deoxy‐Hb had larger fluctuations during REM sleep than those during non‐REM sleep. During REM sleep, oxy‐Hb often showed a lower level and deoxy‐Hb showed a higher level than those during the preceding and following non‐REM sleep.

Screening for mutations at codon 717 of the amyloid precursor protein gene in Alzheimer's disease

Abstract Three kinds of missense mutation at codon 717 of amyloid precursor protein (APP) gene (Val→Ile; Val→Gly; Val→Phe) were screened in 114 patients with familial and sporadic Alzheimers disease (AD), using a rapid testing method for each Val→Gly and Val→Phe mutation and Goates method for Val→Ile mutation based on the polymerase chain reaction. Mutations were not found in the subjects, confirming earlier suggestions that these three mutations at codon 717 of APP gene account for only a small proportion of cases of not only familial AD but also sporadic AD.

Restriction of suicide methods: A Japanese perspective

Abstract Whether legal restriction of access to methods which can be used for suicide will actually reduce the suicide rate has been an issue of debate for years. Among the various methods of suicide, those at the center of debate have been firearms, prescription psychotropic drugs, herbicides, home gas, and automobile exhaust fumes. The opinions on this debate seem to be classified into three: 1) restriction is effective, 2) the effect of restriction is limited or only temporary, 3) restriction is ineffective. This paper reviews the debate briefly and gives some of our considerations on this issue.

In a case of Alzheimer's disease, aggressiveness disappeared after an infarction in the anterior thalamic nucleus.

Case Report In June 2002, a right-handed woman was admitted to the hospital at the age of 91 and showed intense aggressiveness. She was diagnosed as having Alzheimer’s senile dementia at the age of 88 and was associated with delusion and hostility towards the family. She often appeared angry and displayed resistance and violence towards caregivers. At the age of 95, a slightly unstable posture was observed when walking or sitting. A brain MRI was performed and diffusion-weighted imaging showed hyperintensity in a small region within the right basal ganglia, adjacent to the right lateral ventricle ( fig. 1 a). We diagnosed acute brain infarction and administered treatment for 2 weeks. A later MRI ascertained that the infarction caused a restricted lesion in the right anterior thalamic nucleus (ATH) ( fig. 1 b, c). After the infarction, the patient’s emotional and behavioral aggressiveness disappeared; she talked gently with the care staff and received assistance without refusal or aggression. In an assessment based on the Behavioral Pathology in Alzheimer’s Disease Rating Scale [2] , the scores of threat, violence, anxiety and fear decreased by at least 2 points compared to those before the infarction. The Mini-Mental State Examination scores were 5/30 in 2005 before the infarction, 2/30 in July 2006 after the infarction and 17/30 in April 2007. She was discharged in May 2007 and severe aggressiveness has not recurred. Introduction Emotional disturbances including aggressiveness, behavioral abnormalities and violence cause difficulty in the treatment and care of patients with Alzheimer’s disease. Although neuroleptics, including atypical antipsychotics, often alleviate these problems [1] , the mechanisms underlying the aggressive behavior are still unknown in this disease. Published online: November 17, 2008