Makoto Ito

Gunma University, Maebashi, Gunma Prefecture, Japan

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Publications (10)31.34 Total impact

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    ABSTRACT: Daytime sleepiness is considered to be one of the main problems in modern society. Of the four aspects of sleepiness, namely, subjective sleepiness, performance decrease, sleep propensity, and arousal decrease, subjective sleepiness is the most difficult to assess. Brain mechanisms underlying subjective light sleepiness in daytime were investigated in healthy subjects using multichannel near-infrared spectroscopy (NIRS), which enables the noninvasive measurement of regional cerebral blood volume (rCBV) changes under natural conditions. Forty right-handed healthy volunteers participated in this study. Relationships were investigated between subjective sleepiness and anxiety, assessed using the Stanford Sleepiness Scale (SSS) and State-Trait Anxiety Inventory (STAI), respectively, and cerebral cortex reactivities assessed as oxygenated and deoxygenated hemoglobin concentration ([oxy-Hb] and [deoxy-Hb], respectively) changes during a verbal fluency task using a 24-channel NIRS machine. SSS score correlated negatively with an [oxy-Hb] increase in the bilateral frontal channels mainly in the middle and last third of the verbal fluency task period. Subjective light daytime sleepiness in healthy subjects is considered to be related to decreased prefrontal reactivities in the later part of cognitive activation.
    Neuroscience Research 04/2008; 60(3):319-26. DOI:10.1016/j.neures.2007.12.001 · 2.15 Impact Factor
  • Clinical Neurophysiology 12/2007; 58(6). DOI:10.1016/j.neures.2007.06.764 · 2.98 Impact Factor
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    ABSTRACT: The time courses of brain activation were monitored during a finger tapping task using multichannel near-infrared spectroscopy with a time resolution of 0.1s in 30 healthy volunteers. Task-induced brain activations were demonstrated as significant increases in oxygenated hemoglobin concentration ([oxy-Hb]) in a broad area around the motor cortex and significant decreases in deoxygenated hemoglobin concentration ([deoxy-Hb]) in a more restricted area, with a large degree of activation in the contralateral hemisphere. The time courses of the [oxy-Hb] changes varied depending on channel location: sustained activation across the task period in the motor cortex, transient activation during the initial segments of the task period in the somatosensory cortex, and accumulating activation along the task period in the frontal lobe. These characteristics are assumed to reflect the functional roles of the brain structures during the task period, that is, the execution, sensory monitoring, and maintenance of finger tapping.
    Neuroscience Research 08/2007; 58(3):297-304. DOI:10.1016/j.neures.2007.03.014 · 2.15 Impact Factor
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    ABSTRACT: 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.
    NeuroImage 02/2006; 29(1):172-84. DOI:10.1016/j.neuroimage.2005.07.025 · 6.36 Impact Factor
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    ABSTRACT: 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. 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. 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. Increased and decreased brain activations demonstrated using multichannel NIRS were assumed to characterize the cortical reactivities underlying novelty seeking and persistence temperament, respectively.
    Neuropsychobiology 02/2005; 52(1):45-54. DOI:10.1159/000086177 · 2.30 Impact Factor
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    ABSTRACT: 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. 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. 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. 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.
    Biological Psychiatry 04/2004; 55(5):501-11. DOI:10.1016/j.biopsych.2003.09.008 · 10.25 Impact Factor
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    ABSTRACT: Introduction: Abnormalities in the dynamic aspects of brain activity could underlie the pathophysiology of psychiatric disorders. Temporal characteristics of cerebral blood volume change, which are candidate indices of such dynamic aspects, were examined using a multichannel near-infrared spectroscopy (NIRS) machine. Methods: Thirty right-handed healthy volunteers participated in the study (mean age: 27.1±3.0, age range: 22–33; 15 males and 15 females). The relative concentrations of oxy-hemoglobin ([oxy-Hb]) were measured during a 40-s unilateral finger-tapping task using two sets of probes of the 24-channel NIRS machine placed on the subjects' temporal regions with a time resolution of 0.1 s. Grand averaged waveforms of [oxy-Hb] across all subjects were obtained from the individually averaged waveforms for each side of tapping in 24 channels. Results: Temporal characteristics of the [oxy-Hb] increase during the tapping period and were classified into three patterns: (1) slow and gradual increase during the task; (2) sustained increase across the task; and (3) initial peak in the early segment of the task. The channels showing the three patterns corresponded approximately to the primary motor, premotor and primary somatosensory areas, respectively. The extent of contralateral hemisphere activation of the tapping side was greater in the right-finger-tapping task than that found in the left-finger-tapping task. Conclusion: Temporal characteristics of cerebral blood volume change were noninvasively demonstrated to vary among various cortical areas using a multichannel NIRS machine.
    International Congress Series 04/2002; 1232:383-388. DOI:10.1016/S0531-5131(01)00846-9
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    ABSTRACT: Introduction: Brain function characteristics underlying the biological aspect of personality, i.e., “temperament”, have not been fully elucidated. In the present study, we investigated the relationship between temperament and hemodynamic features of the cerebral cortex in healthy subjects using a multichannel near-infrared spectroscopy (NIRS) machine. Methods: Thirty right-handed healthy volunteers participated in the study (age: mean 27.1±3.0 years, range 22–33 years; 15 males, 15 females). Relative concentrations of oxy-hemoglobin ([oxy-Hb]) were monitored during a 40-s unilateral finger tapping task by two sets of 12-channel probes of the NIRS machine placed on the subjects' temporal regions. Correlations between [oxy-Hb] in the 24 channels and the subjects' personality traits assessed with the Temperament and Character Inventory (TCI) were examined. Results and discussion: Increases in [oxy-Hb] during the left finger tapping task were positively correlated with the novelty seeking scores of the TCI, particularly with its disorderliness and impulsiveness sub-scores, in the presumed primary motor area of the left hemisphere, and were negatively correlated with the persistence scores of the TCI mainly in the right hemisphere. No significant correlations were observed for other personality dimensions. Thus, individual differences in cerebral cortex, hemodynamic characteristics were shown to underlie some personality dimensions such as novelty seeking and persistence using the multichannel NIRS machine.
    International Congress Series 04/2002; 1232:71-75. DOI:10.1016/S0531-5131(01)00733-6
  • International Clinical Psychopharmacology 09/2001; 16(5):310-311. DOI:10.1097/00004850-200109000-00067 · 3.10 Impact Factor
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    ABSTRACT: Using functional magnetic resonance imaging (fMRI) we were able to observe, in detail, ictal brain hemodynamics during epileptic seizure caused by a brain tumor. A 53-year-old man was experencing partial motor seizures of the left side of his face and neck. In a brain MR image a mass lesion was found in the subcortical area of the right frontal lobe. We found focal spikes in his right hemisphere, though dominantly in C4 and T4 regions. fMRI investigations were carried out at 1.5 T (GE Signa Horizon) using gradient-echo echo-planar neuroimaging. We were able to perform the ictal examination twice. The activated regions were focalized and clearly found only on the lateral side of the tumor base. The region was in agreement with the epileptic focus examined using an electrocorticogram (ECOG). The signal intensity in the seizure focus rapidly increased 30 seconds before the convulsion was observed. After the end of the convulsion it also took 30 seconds to restore the signal intensity to the baseline value. fMRI is a very useful tool for various studies such as the identification of the epileptic focus, the mechanism of epileptic seizure, and so on.
    Seizure 01/2001; 9(8):585-9. DOI:10.1053/seiz.2000.0464 · 2.06 Impact Factor