Biomedical subjects

Mitsuru Kikuchi

Publications and source records attributed to Mitsuru Kikuchi.

10 recordsLinked to original sources

PubMed2006

State-dependent changes in intrahemispheric EEG coherence for patients with acute exacerbation of schizophrenia.

Abnormalities of electroencephalographic (EEG) coherence in schizophrenia are thought to reflect functional disconnections between different brain regions associated with the onset of this disease. To clarify whether these abnormalities change in a symptom-dependent manner in individual patients, we analyzed the coherence of resting EEGs recorded at two time points with a 36.6-day interval during the course of treatment for 14 patients who had been hospitalized for acute exacerbation of schizophrenia. Symptom severity was quantitatively measured by means of the Brief Psychiatric Rating Scale (BPRS). Beta (13-20 Hz) coherence for the left frontal (F7)-temporal (T5) electrode pair was less than that for the corresponding right pair (F8-T6) at the initial test. At the second test, when symptoms had improved, the left frontal-temporal beta coherence had increased, resulting in disappearance of the laterality. This change in beta coherence for the left frontal-temporal pair correlated negatively with the change in the total BPRS score, particularly the positive symptom score. Similar correlations were found for eight patients who had been drug-free at the first examination. These results suggest that a functional disconnection between the frontal and the temporal lobe in the left hemisphere may be associated with the generation of acute psychotic symptoms in schizophrenia.

Acute Disease↗

PubMed2006

Functional connectivity between hemispheres and schizophrenic symptoms: a longitudinal study of interhemispheric EEG coherence in patients with acute exacerbations of schizophrenia.

To clarify whether interhemispheric electroencephalogram (EEG) coherence reflecting functional connectivity between the two cerebral hemispheres can change in a symptom-dependent manner in schizophrenia, we measured resting EEG and symptom severity twice at an average interval of 32.7 days during the course of treatment in 15 patients hospitalized for acute exacerbations of schizophrenia. Symptom severity was estimated quantitatively by means of the Brief Psychiatric Rating Scale (BPRS). Correlation analysis showed that increases in the beta-band coherence for frontal electrode pairs during the treatment were associated with improvement in the total score and the score on the positive subscale of BPRS. This result suggests that functional disconnection between the left and right frontal lobes may be related to the generation of psychotic symptoms and can normalize following antipsychotic treatment.

Adult↗

PubMed2005

Individual analysis of EEG band power and clinical drug response in schizophrenia.

The main purpose of this study was to investigate the relationship between short-term clinical outcome and changes in electroencephalogram (EEG) power after drug treatment in patients with schizophrenia, and also to compare two different methods for quantitative EEG analysis. EEG power analysis was performed by both conventional fixed frequency band and adjusted frequency band based on individual alpha frequency (IAF) in 16 drug-naive patients before and after drug administration. In the theta bands determined by both conventional fixed band and IAF methods, the EEG power after treatment was larger than that before treatment. In addition, there was a correlation between EEG power and clinical drug response evaluated by changes in BPRS score. With regard to this correlation, IAF methods showed no apparent advantage over methods using conventional fixed frequency bands. Conventional quantitative EEG analysis can still serve as a useful tool for the assessment of short-term outcome of drug treatment.

Adolescent↗

PubMed2005

Changes in EEG and autonomic nervous activity during meditation and their association with personality traits.

Meditation is the attainment of a restful yet fully alert physical and mental state practiced by many as a self-regulatory approach to emotion management, but the psychophysiological properties and personality traits that characterize this meditative state have not been adequately studied. We quantitatively analyzed changes in psychophysiological parameters during Zen meditation in 20 normal adults, and evaluated the results in association with personality traits assessed by Cloninger's Temperament and Character Inventory (TCI). During meditation, increases were observed in fast theta power and slow alpha power on EEG predominantly in the frontal area, whereas an increase in the normalized unit of high-frequency (nuHF) power (as a parasympathetic index) and decreases in the normalized unit of low-frequency (nuLF) power and LF/HF (as sympathetic indices) were observed through analyses of heart rate variability. We analyzed the possible correlations among these changes in terms of the percent change during meditation using the control condition as the baseline. The percent change in slow alpha EEG power in the frontal area, reflecting enhanced internalized attention, was negatively correlated with that in nuLF as well as in LF/HF and was positively correlated with the novelty seeking score (which has been suggested to be associated with dopaminergic activity). The percent change in fast theta power in the frontal area, reflecting enhanced mindfulness, was positively correlated with that in nuHF and also with the harm avoidance score (which has been suggested to be associated with serotonergic activity). These results suggest that internalized attention and mindfulness as two major core factors of behaviors of mind during meditation are characterized by different combinations of psychophysiological properties and personality traits.

Adult↗

PubMed2005

Relationship between anxiety and thyroid function in patients with panic disorder.

The aim of this study was to investigate correlations between thyroid function and severity of anxiety or panic attacks in patients with panic disorder. The authors examined 66 out-patients with panic disorder (medicated, n=41; non-medicated, n=25), and measured their free thriiodothyronine (T3), free thyroxine (T4) and thyroid-stimulating hormone (TSH) levels. Significant correlations between the thyroid hormone levels and clinical features were observed in the non-medicated patients. The more severe current panic attacks were, the higher the TSH levels were. In addition, severity of anxiety correlated negatively with free T4 levels. In this study, we discuss relationship between thyroid function and the clinical severity or features of panic disorder.

Adolescent↗

PubMed2005

Panic disorder with and without agoraphobia: comorbidity within a half-year of the onset of panic disorder.

The present study was performed to compare the clinical features of patients with panic disorder with and without agoraphobia. The subjects were 233 outpatients with panic disorder (99 males and 134 females) diagnosed according to DSM-IV criteria. Sixty-three patients met the criteria for panic disorder without agoraphobia, and 170 met the criteria for panic disorder with agoraphobia. Patients with agoraphobia showed a significantly longer duration of panic disorder and higher prevalence of generalized anxiety disorder. However, there were no significant differences in prevalence of major depressive episodes, in current severity of panic attacks, or in gender ratio between the two groups. The second aim of the present study was to investigate the effects of onset age and sex differences on the development of agoraphobia within a half-year. The subjects were divided into two groups according to their self-report: patients who did or did not develop agoraphobia within 24 weeks of onset of panic disorder. A total of 40.6% of the patients developed agoraphobia within 24 weeks of the onset of panic disorder, and onset age and sex differences had no robust effect on the development of agoraphobia within 24 weeks.

Adult↗

PubMed2005

EEG coherence analysis in never-medicated patients with panic disorder.

To investigate the functional abnormalities in the central nervous system (CNS) of patients with panic disorder (PD), we compared the electroencephalography (EEG) coherence values in 18 never-medicated PD patients with those in age-matched normal control subjects, and examined the relationships between EEG coherence values and both the duration of disease and the severity of panic attacks. EEG data were recorded in the resting state. The PD patients had lower coherence values with significant differences in F3-F4, C3-C4, P3-P4, F7-T5, and F8-T6. There were positive correlations for the higher alpha band between coherence values and both the duration of disease and the severity of panic attacks. These findings provide further evidence that PD patients have a lower degree of inter-hemispheric functional connectivity in the frontal region and intra-hemispheric functional connectivity in the bilateral temporal region, and that chronic condition or frequent panic attacks in PD patients may be related to the pathophysiological CNS changes.

Adult↗

PubMed2003

Sequential EEG analysis during intermittent photic stimulation in never-medicated patients with schizophrenia.

To investigate sequential changes in electroencephalograms (EEGs) during intermittent photic stimulation (IPS), quantitative EEG analysis for the alpha band (related to stimulus frequency) was performed in 18 drug-naïve schizophrenic patients and 18 sex- and age-matched control subjects. IPS consisted of white flickers at 10 flashes/sec, lasting 10 sec and repeated six times at 10 sec intervals. The differences between the two groups were assessed for two conditions (i.e., during photic stimulation (PS) and inter-PS). During stimulus, the absolute 9-11 Hz band power of the patient group was higher at the posterior than that at the anterior sites throughout the 10 sec periods. However, this difference between sites was not seen during the first 1 sec in the control group. During the nonstimulus period, posterior dominance of 9-11 Hz band power was prominent in the patient group throughout. In the control group, however, this difference was minor, especially during the latter half of the period. These results suggest that schizophrenic patients show fewer changes in posterior alpha activity during both stimulus and nonstimulus, and this continuity of posterior dominance may reflect hyperarousal, which counteracts any decrease in vigilance throughout the IPS.

Adolescent↗

PubMed2002

EEG harmonic responses to photic stimulation in normal aging and Alzheimer's disease: differences in interhemispheric coherence.

OBJECTIVES: The distinction between electroencephalogram (EEG) driving responses in normal aging and Alzheimer's disease (AD) is unclear. This study was conducted to explore the structure of harmonic responses of EEG coherence during photic stimulation (PS) in AD. METHODS: EEG interhemispheric coherence was analyzed for each harmonic responses during PS (white flickers at 5, 10 and 15 flashes/sec) in younger subjects (20-25 years), non-demented elderly subjects (50-67 years) and AD patients (43-66 years). RESULTS: The elderly subjects had higher interhemispheric coherence during PS than the younger subjects, with significant differences found in the 6th (30Hz) and 8th (40Hz) harmonic responses to 5Hz PS. The AD patients had significantly smaller coherence than the elderly subjects in the 2nd (10Hz) and 4th (20Hz) harmonic responses to 5Hz PS, and in the fundamental (10Hz) and 2nd (20Hz) harmonic responses to 10Hz PS. These coherence values did not correlate with duration of the disease or with cognitive functioning as evaluated by MMSE score. CONCLUSIONS: A failure of stimulation-related brain activation in AD patients was observed in alpha-related frequencies, suggesting that AD is not the end result of normal aging of the brain, at least in terms of the mechanisms which are involved in PS-related functional organization.

Aged↗

PubMed2002

Differences in EEG harmonic driving responses to photic stimulation between normal aging and Alzheimer's disease.

In order to investigate whether Alzheimer's disease (AD) is the end result of aging of the brain or the result of some other mechanism, we analyzed EEGs showing the absolute power of harmonic responses to photic stimulation (PS) in younger subjects, non-demented elderly subjects and AD patients. At rest, the AD patients generally showed less absolute power than the younger and elderly subjects, with significant differences found at 10 Hz and 20 Hz. Analysis of EEGs recorded during PS indicated that the elderly subjects generally demonstrated more absolute power than the younger subjects and AD patients. These findings suggest a failure of stimulation-related brain activation in AD patients, and provide further evidence that normal aging and AD employ different mechanisms for functional organization during PS.

Adult↗