Katsumi Nakamura

Kagoshima University, Kagosima, Kagoshima, Japan

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Publications (13)21.82 Total impact

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    ABSTRACT: We studied the imaginary coherence (IC) of gamma frequency oscillations between brain regions of male schizophrenia patients during an auditory oddball task using magnetoencephalography (MEG) and electroencephalography (EEG). Subjects were 10 right-handed male schizophrenia patients, evaluated by the positive and negative symptom scale (PANSS), and 10 healthy controls. Functional connectivity during the auditory oddball task was reconstructed in low (30-50 Hz) and high (50-100 Hz) gamma bands, and represented by imaginary coherence (IC) based on significant oscillatory power changes. We calculated correlations between PANSS scores and IC. In the high gamma band, IC between left occipital and right prefrontal lobe areas during the time window 750-1000 ms from stimulus onset showed negative correlations with total negative scores, total positive scores, the sum of positive and negative scores in PANSS, conceptual disorganization, and social avoidance scores. In the low gamma band, IC between the same areas from 250-500 ms also showed a negative correlation with the conceptual disorganization score. In the same time window, IC between left occipital and right frontoparietal lobe areas in the low gamma band showed a positive correlation with hallucinatory behavior; IC between right temporal pole and left prefrontal lobe areas showed a positive correlation with delusion scores, although these ICs were decreased relative to controls. Functional disconnection of high and low gamma bands in auditory oddball task may play an important role in the auditory processing in schizophrenia patients.
    The Open Neuroimaging Journal 01/2013; 7:15-26.
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    ABSTRACT: We studied differences in the spatiotemporal dynamics of cortical oscillation across brain regions of patients with schizophrenia and normal subjects during the auditory oddball task using magnetoencephalography (MEG) and electroencephalography (EEG). Ten right-handed male schizophrenia patients were studied. We used a newly developed adaptive spatial filtering algorithm optimized for robust source time-frequency reconstruction of MEG and EEG data, and obtained consecutive images in functional maps of event-related desynchronization (ERD) and synchronization (ERS) in theta, lower alpha (8-10 Hz), upper alpha (10-13 Hz), and beta bands. Beta ERD power at 750-1000 ms in patients was significantly increased in large right upper temporal and parietal regions and small upper portions of bilateral dorsal frontal and dorsal-medial parietal regions. Theta ERS power in schizophrenic patients during the oddball task was significantly increased in the left temporal pole at 250-500 ms, and was significantly increased in dorsal, medial frontal, and anterior portions of the anterior cingulate cortex in both hemispheres, and the left portion of lateral temporal regions at 500-750 ms, compared to the control group (family-wise error correction p<0.05). Lower alpha ERS power was significantly decreased in the right occipital region at 500-750 ms and in the right midline parietal and bilateral occipital regions at 750-1000 ms. Upper alpha ERS power was significantly decreased in right midline parietal and left occipital regions at 750-1000 ms. ERD/ERS changes were noted in the left temporal pole and midline frontal and anterior cingulate cortex in theta ERS, occipital lobe in alpha ERS, and right temporal-frontal-parietal, midline frontal, and anterior cingulate cortex in beta ERD. These findings may reflect disturbances in interaction among active large neuronal groups and their communication with each other that may be related to abnormal cognitive and psychopathological function. Study of ERD and ERS by time-frequency analyses using MEG is useful to clarify data processing dysfunction in schizophrenia.
    The Open Neuroimaging Journal 01/2012; 6:26-36.
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    ABSTRACT: A 26-year-old man presented with a xanthogranuloma located exclusively in the suprasellar region manifesting as general fatigue, bitemporal hemianopsia, and polyuria. Endocrinological examination disclosed severe hypopituitarism. Magnetic resonance imaging demonstrated a clearly defined suprasellar mass that was heterogeneously enhanced after gadolinium administration and was markedly hypointense on T(2)-weighted images. The tumor was subtotally removed under a preoperative diagnosis of craniopharyngioma. Histological examination found fibrous tissue with abundant cholesterol clefts, multinucleated giant cells, and hemosiderin deposits, but no epithelial cells. Xanthogranulomas of the sellar region are reported to be predominantly located in the sella turcica, but should be included in the differential diagnosis even in cases of suprasellar mass lesions.
    Neurologia medico-chirurgica 04/2009; 49(3):124-7. · 0.49 Impact Factor
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    ABSTRACT: Using [(18)F]fluoro-deoxy-glucose-PET, we studied relative metabolic changes due to age- and gender-related differences in the brain of 126 healthy subjects from their twenties to seventies. We used a data-extraction technique, the three-dimensional stereotactic surface projections (3D-SSP) method, to measure metabolic changes with fewer effects of regional anatomic variances. Simple regression analysis revealed significant age-related increases in relative metabolic values in the parahippocampal and amygdala regions in both sexes in their twenties to forties, and significant age-related decreases in both sexes in their fifties to seventies. Relative values in the frontal lobe showed significant age-related decreases in both sexes in their twenties to forties, but these effects were not seen in subjects in their fifties to seventies. Significant gender differences in correlation coefficients of relative values with age were shown in the parahippocampal, primary sensorimotor, temporal, thalamus and vermis regions in subjects in their 20s to 40s, but disappeared in subjects in their twenties to forties, but were not apparent in subjects in their fifties to seventies except in the vermis. Males in their twenties to sixties and females in their fifties showed significant laterality in relative values in the temporal lobes. Our study demonstrated age- and gender-related differences in glucose metabolism in healthy subjects.
    Psychiatry Research 10/2008; 164(1):58-72. · 2.68 Impact Factor
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    ABSTRACT: Purpose: Recently, proton magnetic resonance spectroscopy (1H-MRS) demonstrated neuronal loss or dysfunction in the epileptogenic focus in temporal lobe epilepsy, and bilateral neuronal abnormalities in the temporal lobes. It is well-known that a schizophrenia-like epileptic psychosis is closely related to temporal lobe epilepsy and that the symptoms of a schizophrenia-like epileptic psychosis are extremely similar to those of schizophrenia. We also reported neuronal dysfunction in the basal ganglia of patients with chronic schizophrenia. The basal ganglia play an important role in neuronal circuitry and receive projections from the temporal cortex. We investigated whether there is neuronal dysfunction in the basal ganglia of patients with a schizophrenia-like epileptic psychosis, temporal lobe epilepsy, and schizophrenia, by using the 1H MRS.Methods: Nine patients with a schizophrenia-like epileptic psychosis, seven patients with temporal lobe epilepsy showing no schizophrenia-like symptoms, 14 patients with positive symptoms of schizophrenia, and 10 control subjects were examined. Using the 1H-MRS system with 2 Tesla, 1H spectra were acquired from voxels of the left and right basal ganglia with a size of 2.5 × 2.5 × 2.5 cc. The pulse sequence was stimulated echo (STEAM) with TR = 2,000 ms, TE = 60 ms, and acquisition = 400. Peak areas of N-acetylaspartate (NAA), creatine plus phosphocreatine (Cr), and choline-containing compounds (Cho) were studied.Results: Mean NAA/Cr ratios in the right basal ganglia were 1.07 (schizophrenia-like epileptic psychosis), 1.08 (schizophrenia) and 1.I4 (temporal lobe epilepsy), all of which were significantly decreased, compared with those of control subjects (1.41). Mean NANCr ratios in the left basal ganglia were 1.16 (schizophrenia-like epileptic psychosis), 1.19 (schizophrenia), and 1.24 (temporal lobe epilepsy), all of which were significantly decreased, compared with those of control subjects (1.61). NAA/Cho and NAA/(Cr + Cho) ratios in the right and left basal ganglia were also significantly decreased in patients with a schizophrenia-like epileptic psychosis, temporal lobe epilepsy, or schizophrenia, compared with those of controls. However, there were no significant differences among the NAA/Cr, NAA/Cho, and NAN (Cr + Cho) ratios in patients with a schizophrenia-like epileptic psychosis, temporal lobe epilepsy, or schizophrenia. Decreased levels of NAA demonstrated neuronal dysfunction of the basal ganglia in patients with a schizophrenia-like epileptic psychosis, temporal lobe epilepsy, or schizophrenia, and that neuronal dysfunction in the temporal lobes may cause these changes. These results suggested that neuronal dysfunction of the basal ganglia may reflect disturbances of information processing such as contextual analysis of the environment, and the planning and execution of intelligent behaviors, and may have a close relation with the psychopathological state in a schizophrenia-like epileptic psychosis and schizophrenia. However, the finding that NAA/Cr ratios were decreased, even in the patients with the complex partial seizures of temporal lobe epilepsy without schizophrenia-like symptoms, indicated that the effects of the psychopathological state due to neuronal dysfunction in the basal ganglia are complicated.Conclusions: Neuronal dysfunction in the basal ganglia was found in patients with a schizophrenia-like epileptic psychosis, temporal lobe epilepsy, and schizophrenia.
    Epilepsia 06/2008; 39(S5):58 - 58. · 3.96 Impact Factor
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    ABSTRACT: Changes in glucose metabolism were studied in the brains of schizophrenic patients treated with neuroleptics, using [(18)F]fluoro-deoxy-glucose positron emission tomography (FDG-PET). Fourteen male and eight female patients in their thirties and forties were studied in a resting state. Data from FDG-PET were processed with an anatomic standardization method, three-dimensional stereotactic surface projections (3D-SSP), which provided relative glucose metabolic values that mitigated the contamination of brain atrophy. Z-score maps indicating metabolic differences between the patient and control groups were also acquired. Metabolic values in 19 regions were evaluated in the right and left hemispheres. Patients showed decreased values in the frontal cortex, primary sensory regions and anterior cingulate cortex, more in the rostral affective subdivision than the dorsal cognitive subdivision in both hemispheres, and increased metabolic values in left and right basal ganglia, left temporal and right medial parietal regions. Values were more decreased in both anterior cingulate regions, and more increased in the right thalamus in male than female patients, suggesting gender-related dysfunction in the anterior cingulate and thalamus in schizophrenia. FDG-PET demonstrated that schizophrenia may be a disorder with a dysfunction of fronto-striatal-thalamic circuitry including the cingulate cortex.
    Psychiatry Research 02/2007; 154(1):49-58. · 2.68 Impact Factor
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    ABSTRACT: We examined the periodic synchronous characteristic response to photic stimulation in schizophrenia using electroencephalography (EEG) and magnetoencephalography (MEG). We tested whether neural synchronization deficits were present in subjects with schizophrenia using photic stimulation to evaluate the frequency entrainment in 18 normal subjects and 19 schizophrenia patients. A conventional vertical-type 160-channel MEG (PQ1160C, Yokogawa Electric Corporation) was used. Photic stimulation was at frequencies from 8 to 10.5 Hz at intervals of 0.5 Hz. There were ten stimuli at each frequency, and each lasted 10 seconds. The power spectrum at each site was based on the international 10/20 derivation. The power spectrum in schizophrenia patients was smaller than that in normal subjects at each site. A gender difference was observed in normal subjects, but not in schizophrenia patients. MEG, like EEG, is an effective method for research on neuropathy of the psyche.
    Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference 02/2004; 6:4465-8.
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    ABSTRACT: In order to investigate the efficacy and the safety of vagus nerve stimulation for refractory partial epileptic seizures, a cooperative study was performed in seven institutes of Japan from 1993 to 2000. Thirty-four patients were subjected to this NCP implantation study. The short-term observations for 6 months and the long-term observation of more than 5 years revealed that this treatment was safe and effective for partial epileptic seizures, although there were some drop-out cases on the time courses.
    International Congress Series 01/2002; 1247:471-479.
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    ABSTRACT: Purpose: Since 1993, we have studied the efficacy and safety of vagus nerve stimulation (VNS) with a Neurocyberhetic Prosthesis (NCP) (Cyberonics, U.S.A.) against medically intractable epilepsy first in Japan. We summarize the intermediate results so far acquired in this report.Methods: Patients with intractable partial seizures were selected as candidates for implantation of the NCP. This type of therapy has been tested in individuals whose seizure activity has not been effectively controlled by pharmacotherapy. The result was a reduction in the rate of seizures in each period compared with the average number of seizures before implantation of the NCP. To avoid nerve fatigue, the upper limits of the parameters were set as follows: frequency, 30 Hz; pulse width, 1,000 μ; on time, 60 s; output current, 3.0 mA. After informed consent, the leads of the NCP were connected under general anesthesia to the cervical portion of the left vagus nerve. Those leads were connected through a subcutaneous tunnel with the NCP implanted subcutaneously on the breast. Thirty-four patients have been implanted with the NCP, and 31 patients have started stimulation as of September, 1997. We have analyzed the data from 16 male and 15 female patients who were followed up for >6 months with a mean follow-up period of 20.0 months; their ages ranged from 19 to 52 years with a mean age of 31.2 years. Their types of seizures included 28 complex partial seizures (CPSs), 12 simple partial seizures (SPSs) and 11 secondarily generalized seizures (SGSs). The number of seizures during a month was counted for 3 consecutive months before implantation of NCP. These values were compared with average number of seizures that occurred during the 4–6 months after VNS. We also calculated the patients with a 50% reduction in seizure frequency compared with the baseline.Results: the mean seizure-changing rates during the 4–6 months after stimulation were −26.4 2 13.2% (mean ± SEM) in total seizure numbers, −41.9 ± 13.0% in seizure with disturbance of consciousness, −37.0 ± 19.9% in SGSs, −70.4 ± 17.6% in CPSs, and −15.5 ± 16.2% in SPSs. The 50% reduction rates were 48.4% for all seizure types, 63.3% in seizures with disturbance of consciousness, 58.6% in CPSs, 63.6% in SGSs, and 47.1% in SPSs during the 4 4 months after stimulation.Conclusions: Our early results demonstrated the efficacy and safety of VNS with the NCP in medically intractable epilepsy. We adpated the VNS for intractable epilepsy, and our results demonstrated its efficacy. The reduction of seizures was observed more strongly in the latest 3 months than during the 4–6 months after starting the VNS. This result may be due to the characteristics of VNS or the period when we needed to adjust the parameters of the NCP. The efficacy of VNS during the latest 3 months is better than that of recent antiepileptic agents. However, we have not yet achieved any seizure-free patients, although their seizure rates have been reduced. We need more experiences with VNS to determine the appropriate parameters and find out how to select the most suitable cases.
    Epilepsia 01/1998; 39:61-62. · 3.96 Impact Factor
  • Epilepsia 01/1996; 37:86-87. · 3.96 Impact Factor
  • Psychiatry and Clinical Neurosciences 06/1995; 49(3). · 2.04 Impact Factor
  • Psychiatry and Clinical Neurosciences 06/1992; 46(2):467-469. · 2.04 Impact Factor
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    ABSTRACT: BACKGROUND: An intimate relationship between depressive disorders and chronic pain is well known but often neglected. We studied patients with depres-sive disorders accompanying cervical muscular ten-sion or neck pain. They also complaints of various physical, psychosomatic, and psychiatric signs such as anxiety and non-specific complaints related to auto-nomic imbalance. These complaints or symptoms are commonly resistant to pharmacological treatment, and thus we tried to treat these conditions by reduc-ing their cervical muscular tension or pain. METH-ODS: We evaluated 30 complaints of 138 patients suf-fering from depressive disorders with cervical mu-scular abnormality (52 men and 86 women). The pre-sence of the 30 complaints was evaluated as "positive" or "negative" before and during treatment. The necks of all patients were treated using low-frequency sti-mulation, micro-wave therapies, electric needle appli-cation, and acupuncture. RESULTS: Reducing cer-vical muscular tension remitted or cured the 30 com-plaints including depressive mood. The reduction of cervical muscle pain or tension initially ameliorated the depressive symptoms and anxiety, and subse-quently improved their autonomic imbalances. Dis-criminant analysis of the first and second examina-tions correctly classified 95.3% of original grouped cases. CONCLUSION: Reducing cervical muscular tension is an effective treatment for patients suffering from depressive disorders with cervical neuromuscu-lar pain or hardness.