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Masato Fukuda

Publications and source records attributed to Masato Fukuda.

At least 19 recordsLinked to original sources
PubMed2006

Comparison between mismatch negativity amplitude and magnetic mismatch field strength in normal adults.

The auditory mismatch negativity (MMN) or its magnetic counterpart (magnetic mismatch field, MMF) has been widely used to assess the ability of stimulus-driven change detection process in humans. The authors evaluated the similarity of inter-individual variation of the response strength between MMN and MMF recordings. Three types of MMN or MMF were recorded in ten healthy subjects: change in duration of pure-tone stimuli, change in duration of the Japanese vowel /a/, and difference between the Japanese vowels /a/ and /o/. There was no significant correlation between MMN amplitude and MMF strength under any condition and in either hemisphere. These results suggest that widely used indices of MMN in the two technologies, i.e., EEG-amplitude and MEG-ECD may not be proportional in an individual. To further clarify the differential significance of recording MMN/MMF may be important to establish MMN/MMF as clinical indices of individual ability of preattentive stage of auditory processing.

Adult↗
PubMed2006

[Clinical availability of biological markers for diagnosis of schizophrenia: reactivity of frontal lobe function assessed with near-infrared spectroscopy].

Biological markers of psychiatric disorders can be employed both for research and clinical purposes, are classified into state, trait, and morbid markers, and are expected to be useful in diagnosis, treatment, and prediction of psychiatric disorders in clinical settings. Near-infrared spectroscopy that can measure reactivity of cerebral cortex function is one of biological markers for clinical purposes, and has revealed characteristic patterns of frontal lobe function in psychiatric disorders. Availability of biological makers for diagnosis of psychiatric disorders was examined by reviewing effect sizes of various biological markers in schizophrenia, showing that more elaborated markers for higher brain functions are promising: cognition (1.0-1.4), neurophysiology (0.8-1.0), functional brain imaging (0.6-0.8), and structural brain imaging (0.5-0.6).

Biomarkers↗
PubMed2005

Frontal lobe function in bipolar disorder: a multichannel near-infrared spectroscopy study.

Frontal lobe dysfunction has been implicated as one of the pathophysiological bases of bipolar disorder. Detailed time courses of brain activation in the bipolar disorder group were investigated using multichannel near-infrared spectroscopy (NIRS), a recently developed functional neuroimaging technology with a high time resolution, and were compared with those in the major depression and healthy control groups. Seventeen patients with bipolar disorder, 11 equally depressed patients with major depression, and 17 healthy controls participated in the study. Changes in oxy hemoglobin concentration ([oxy-Hb]) during cognitive and motor tasks were monitored using frontal and temporal probes of two sets of 24-channel NIRS machines. [oxy-Hb] increases in the bipolar disorder group were smaller than those in the healthy control group during the early period of a verbal fluency task, larger than those in the major depression and healthy control groups during the late period of this task, and were smaller than those in the major depression group during a finger-tapping task. Depressive symptoms and antidepressant dosages did not correlate with [oxy-Hb] changes in the two patient groups. Bipolar disorder and major depression were characterized by preserved but delayed and reduced frontal lobe activations, respectively, in the present high-time-resolution study by multichannel NIRS.

Adult↗
PubMed2005

Increased and decreased cortical reactivities in novelty seeking and persistence: a multichannel near-infrared spectroscopy study in healthy subjects.

BACKGROUND: Near-infrared spectroscopy (NIRS) has enabled completely noninvasive measurements of regional cerebral blood volume (rCBV) changes in cortices. In the present study, we investigated the relationships between rCBV changes assessed with NIRS and two dimensions of personality, novelty seeking and persistence. METHODS: Thirty right-handed healthy volunteers participated in the study. Their personality traits were assessed using the Temperament and Character Inventory (TCI), and changes in oxy- and deoxy-hemoglobin concentrations were monitored during 40 s unilateral finger tapping tasks over the subjects' bilateral temporal regions using a 24-channel NIRS machine. RESULTS: The oxy-hemoglobin concentration increases were significantly correlated positively with novelty seeking scores and negatively with persistence scores in the TCI during the initial time segment of the left-finger tapping task. CONCLUSION: Increased and decreased brain activations demonstrated using multichannel NIRS were assumed to characterize the cortical reactivities underlying novelty seeking and persistence temperament, respectively.

Adult↗
PubMed2005

Delayed automatic detection of change in speech sounds in adults with autism: a magnetoencephalographic study.

OBJECTIVE: Autism is a form of pervasive developmental disorder in which dysfunction in interpersonal relationships and communication is fundamental. This study evaluated neurophysiological abnormalities at the basic level of language processing, i.e. automatic change detection of speech and non-speech sounds, using magnetoencephalographic recording of mismatch response elicited by change in vowels and tones. METHODS: The auditory magnetic mismatch field (MMF) was evaluated in 9 adults with autism and 19 control subjects using whole-head magnetoencephalography. The MMF in response to the duration change of a pure tone or vowel /a/ and that in response to across-phoneme change between vowels /a/ and /o/, were recorded. RESULTS: The groups were not significantly different in MMF power under any conditions. However, the autism group showed a left-biased latency prolongation of the MMF particularly under the across-phoneme change condition, and this latency delay was significantly associated with greater symptom severity. CONCLUSIONS: These results suggest that adults with autism are associated with delayed processing for automatic change detection of speech sounds. These electrophysiological abnormalities at the earliest level of information processing may contribute to the basis for language deficits observed in autism. SIGNIFICANCE: These results provide the first evidence for delayed latency of phonetic MMF in adults with autism.

Acoustic Stimulation↗
PubMed2005

Electrophysiological indices associated with social functioning outcome in schizophrenia: a 5-year follow-up study.

We previously demonstrated that event-related potentials (ERPs), such as N1/N2b amplitudes in an auditory selective attention task, were significantly associated with communication skills of schizophrenia. The present study investigated the relationship between N1/N2b amplitudes and the quality of life (QOL) 5 years after ERP measurement. QOL of 15 patients with schizophrenia was assessed using the quality of life scale (QLS). Correlational analyses revealed a significant relationship between N2b, but not N1, amplitude and specific domains of QOL. N2b amplitude, an electrophysiological index of orienting response, may be associated with longitudinal social functioning outcome in schizophrenia.

Acoustic Stimulation↗
PubMed2004

Brain electric activity for active inhibition of auditory irrelevant information.

We applied high resolution event-related potentials (ERPs) to assess brain activities associated with inhibition of irrelevant information processing during auditory selective attention. Ten healthy subjects performed an auditory selective attention task. ERPs in response to standard stimuli delivered to the unattended ear (irrelevant stimuli) and those delivered to the attended ear (relevant stimuli) were evaluated using temporally sequential scalp current density (SCD) mappings. For the irrelevant stimuli, current sources were located in the mid-frontal regions at 140-220 ms post-stimuli, and these SCD values were significantly larger than those for the relevant stimuli. These results suggest that auditory selective attention process involves not only focusing attention on relevant information, but also inhibitory processing of irrelevant information mediated by the frontal cortex.

Adult↗
PubMed2004

Multichannel near-infrared spectroscopy in depression and schizophrenia: cognitive brain activation study.

BACKGROUND: Recent developments in near-infrared spectroscopy (NIRS) have enabled the noninvasive clarification of brain functions in psychiatric disorders with measurement of hemoglobin concentrations as cerebral blood volume. METHODS: Ten patients with depression, 13 patients with schizophrenia, and 16 age- and gender-matched healthy control subjects participated in the study after giving consent. The relative concentrations of oxyhemoglobin [oxyHb] were measured with frontal and temporal probes every.1 sec during word fluency and unilateral finger tapping tasks, with two 24-channel NIRS machines. RESULTS: The [oxyHb] increase patterns during the word fluency task varied among the three groups, although their task performances were similar: the depression group was characterized by a smaller [oxyHb] increase during the first half of the task period and the schizophrenic group by a small trough of [oxyHb] at the start of the task period and [oxyHb] re-increase in the posttask period. [OxyHb] increases during the finger-tapping task were rather larger in the patient groups than in the control group. CONCLUSIONS: The characteristic time courses of [oxyHb] changes in the frontal lobe were elucidated for depression and schizophrenia. Near-infrared spectroscopy, with its noninvasiveness and high time resolution, can be a useful tool for research and clinical purposes in psychiatry.

Adult↗
PubMed2004

Effects of corollary discharge on event-related potentials during selective attention task in healthy men and women.

Corollary discharge is a brain electrical activity associated with self-monitoring, which distinguishes self from others in thoughts or behaviors. Corollary discharge can be non-invasively assessed using event-related potential (ERP) recordings in humans. Previous studies have revealed that the amplitude of the N100 component elicited during an "odd-ball" task is reduced while a healthy subject is vocalizing, which may index the effect of corollary discharge on auditory ERPs. In this study, we attempted to assess the effect of vocalization on ERP components including N100, mismatch negativity (MMN), negative difference wave (Nd), and P300 during a selective attention task in 22 healthy adults. We also evaluated the possible contribution of gender to these effects. N100 amplitudes elicited by unattended standard stimuli were reduced under the vocalization condition compared with those under the baseline condition. However, there were no significant effects of vocalization on MMN, Nd or P300. Moreover, there was no significant effect of gender to the corollary discharge. These results suggest that the effect of corollary discharge on auditory ERPs is limited to the perceptual stage of information processing in healthy men and women.

Acoustic Stimulation↗
PubMed2004

Executive and prefrontal dysfunction in unipolar depression: a review of neuropsychological and imaging evidence.

This paper reviews recent empirical findings related to prefrontal and executive function in unipolar depression. While a number of reviews have dealt with either the neuropsychological literature or findings from imaging studies, the present review addresses both, as well as findings from studies that have combined brain-imaging techniques with neuropsychological measures. This combined approach is of great interest as the performance of a structured task may act to load the areas of interest and reduce variance, thus making the imaging evidence more valuable; while the use of imaging provides a check that the neuropsychological tasks are indeed engaging the structures whose performance they are intended to assess. Prominent models of the neurobiology of depression implicate involvement of the anterior cingulate cortex (ACC) and the dorsolateral prefrontal cortex (DLPFC). The evidence from combined imaging and neuropsychological studies supports the involvement of the ACC, but is less clear in the case of the DLPFC. However, the limited number of such studies conducted to date means that conclusions must be tentative and further studies employing this combined approach may be of great value.

Animals↗
PubMed2004

Sex and age dependencies of cerebral blood volume changes during cognitive activation: a multichannel near-infrared spectroscopy study.

In this study, we measured the change in cerebral hemoglobin concentrations during a cognitive task using multichannel near-infrared spectroscopy (NIRS), and investigated the relationship between regional cerebral blood volume and sex, age, and task performance. Thirty-nine healthy volunteers (24 males and 15 females; mean age, 33.0 years) participated after giving their informed consent and performed a word fluency task. The relative oxy-hemoglobin concentration ([oxy-Hb]) was measured using frontal and temporal probes with two sets of 24-channel NIRS machines. The effects of sex, age, and task performance on [oxy-Hb] changes were analyzed using analysis of covariance: with sex, age, and task performance as independent variables, and [oxy-Hb] changes as dependent variables, and years of education as covariates. The effects on [oxy-Hb] increase were significant in many channels in the frontal and temporal probes for sex, that is the most prominent effect, and in a few frontal channels for age: [oxy-Hb] increases were larger in males than in females, and in the young than in the middle-aged. The effects on [oxy-Hb] increase were not significant for task performance, but [oxy-Hb] increases in subjects with low performance tended to be larger than those in subjects with high performance. The results demonstrated that multichannel NIRS could detect cerebral activation during cognitive tasks and clarify sex- and age-dependent differences in such cerebral activation. Sex- and age-dependent differences in cerebral activation, as demonstrated in the present study, should be considered when interpreting cerebral blood volume, cerebral blood flow, and cerebral glucose metabolism data.

Adult↗
PubMed2003

Neuromagnetic correlates of impaired automatic categorical perception of speech sounds in schizophrenia.

Schizophrenia is associated with dysfunction in language processing. At the earliest stage of language processing, dysfunction of categorical perception of speech sounds in schizophrenia has been demonstrated in a behavioral task. The aim of this study was to assess automatic categorical perception of speech sounds as reflected by event-related changes in magnetic field power in schizophrenia. Using a whole-head magnetoencephalographic recording, the magnetic counterpart of mismatch negativity (MMNm) elicited by a phonetic change was evaluated in 16 right-handed patients with chronic schizophrenia and in 19 age-, sex-, and parental socioeconomic status-matched normal control subjects. Three types of MMNm (MMNm in response to a duration decrement of pure-tone stimuli; a vowel within-category change [duration decrement of Japanese vowel /a/]; vowel across-category change [Japanese vowel /a/ versus /o/]) were recorded. While the schizophrenia group showed an overall reduction in magnetic field power of MMNm, a trend was found toward more distinct abnormalities under the condition of vowel across-category change than under that of duration decrement of a vowel or tone. The patient group did not show abnormal asymmetries of MMNm power under any of the conditions. This study provides physiological evidence for impaired categorical perception of speech sounds in the bilateral auditory cortex in schizophrenia. The language-related dysfunction in schizophrenic patients may be present at the early stage of auditory processing of relatively simple stimuli such as phonemes, and not just at stages involving higher order semantic processes.

Adult↗
PubMed2003

[Establishing biological markers for diagnosis and treatment of depression: possible availability of PET, NIRS, and DST].

Current diagnosis of depression depends on its clinical symptoms and signs, not on the results of any laboratory examinations. Establishing biological markers for diagnosis and treatment of depression is one of the most important problems to be solved in psychiatry practice. Near infrared spectroscopy(NIRS) is one of the recently developed methodologies, and can measure cerebral blood volumes simultaneously in multiple points with high time resolution. Multi-channel NIRS machines for clinical use have recently been developed by two medical companies in Japan. Authors presented the preliminary NIRS data showing that depression is characterized by decrease in cerebral blood volume activation during a word fluency task, and discussed their possible availability for diagnosis of depression.

Depression↗
PubMed2002

Prediction and assessment of extrapyramidal side effects induced by risperidone based on dopamine D(2) receptor occupancy.

In the present study, we attempted to predict the risk of extrapyramidal side effects of a selective monoaminergic antagonist, risperidone, by analyzing the correlation between the dopamine D(2) receptor occupancy and the degree of extrapyramidal side effects of the drug. The occupancies of D(2) and 5-HT(2) receptors at various doses of risperidone were calculated by means of a receptor occupancy theory. The extrapyramidal side effects after administration of risperidone were attempted to predict by theoretical analysis of the correlation between the calculated occupancies and the evidence of extrapyramidal symptoms using a ternary complex model. The pharmacokinetic/pharmacodynamic analysis utilized the data concerning the pharmacokinetics of risperidone and 9-hydroxyrisperidone (active metabolite), their binding affinities with D(2) and 5-HT(2) receptors, and the clinical evidence of extrapyramidal symptoms (Extrapyramidal Symptom Rating Scale: ESRS), gathered from the literature. The mean occupancy of 5-HT(2) receptors after the administration of regular doses of risperidone was suggested to be more than 90%, whereas the mean occupancy of D(2) receptors varied between 50-80%, depending on the dose. The correlation between the occupancy of D(2) receptors and the extrapyramidal symptoms could be successfully analyzed with a ternary complex model, showing the predictability of the model for the extrapyramidal side effects of risperidone. Since the estimated risk of the extrapyramidal side effects varied with the dose, the present method of predicting the extrapyramidal side effects of risperidone may provide a basis for developing a rational dosing regimen for the drug.

Antipsychotic Agents↗
PubMed2002

P300 amplitude over temporal regions in schizophrenia.

To examine the left temporal scalp area reductions of P300 amplitude, event-related potentials (ERPs) during a standard oddball task were recorded in 57 schizophrenic patients and 33 normal controls. The P300 amplitude at T3 was not significantly smaller than that at T4 in schizophrenic patients. In the ANOVA analysis of the P300 peak amplitude and PCA factor scores, significant lateral topographical differences in P300 were not present between patients and controls. However, in schizophrenia, patients in the low T3 P300 group were older and consuming higher doses of antipsychotic medicine than those in the high T3 P300 group, and they had relatively low P300 amplitudes and significantly delayed P300 latency, compared with those in the high T3 P300 group. These findings suggested that although the reduction in the left temporal P300 amplitude did not necessarily exist in schizophrenic patients, it may be associated with the severity of the disease process and/or impairment of cognitive function.

Adult↗
PubMed2002

Psychophysiological index during auditory selective attention correlates with visual continuous performance test sensitivity in normal adults.

The continuous performance test (CPT) provides a reliable index of cognitive function, but it is still unclear what aspects of processing this test measures. This study aimed to investigate the contribution of different aspects of cognitive function to the performance on degraded stimulus CPT (DSCPT), which requires a higher level of mental effort than the conventional CPT. Event-related potential (ERP) components, MMN, N2b, and early and late Nds were measured at 16 electrode sites in 19 right-handed normal volunteers using an auditory selective attention task. The association between CPT sensitivity ratings (sensitivity A') and amplitudes of each component was examined for each electrode site. The CPT sensitivity A' showed a significant positive correlation with the N2b amplitude in the fronto-central and temporal regions, predominantly in the right hemisphere and specifically to the right ear of stimulation. This finding suggests that the controlled deviance detection process was related to DSCPT performance.

Acoustic Stimulation↗
PubMed2002

Neuroanatomy and neurophysiology in schizophrenia.

Schizophrenia is a major mental disorder, characterized by their set of symptoms, including hallucinatory-delusional symptoms, thought disorder, emotional flattening, and social withdrawal. Since 1980s, advances in neuroimaging and neurophysiological techniques have provided tremendous merits for investigations into schizophrenia as a brain disorder. In this article, we first overviewed neuroanatomical studies using structural magnetic resonance imaging (s-MRI), MR spectroscopy (MRS), and postmortem brains, followed by neurophysiological studies using event-related potentials (ERPs) and magnetoencephalography (MEG), in patients with schizophrenia. Evidences from these studies suggest that schizophrenia is a chronic brain disorder, structurally and functionally affecting various cortical and subcortical regions involved in cognitive, emotional, and motivational aspects of human behavior. Second, we reviewed recent investigations into neurobiological basis for schizophrenic symptoms (auditory hallucinations and thought disorder) using these indices as well as hemodynamic assessments such as positron emission tomography (PET) and functional MRI (f-MRI). Finally, we addressed the issue of the heterogeneity of schizophrenia from the neurobiological perspective, in relation to the neuroanatomical and neurophysiological measures.

Brain↗