Eiichi Naito

National Institute of Information and Communications Technology, Edo, Tōkyō, Japan

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Publications (71)239.41 Total impact

  • Satoshi Hirose, Isao Nambu, Eiichi Naito
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    ABSTRACT: We propose a solution for over-pruning called Iterative recycling (iRec).•iRec is a novel ensemble learning method for sparse algorithms.•In iRec, classifiers are trained iteratively by recycling over-pruned voxels.•In our experiments, iRec rectified over-pruning in Sparse Logistic Regression.•iRec is applicable to any kind of sparse method.
    Journal of Neuroscience Methods. 11/2014;
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    ABSTRACT: Internal (neuronal) representations in the brain are modified by our experiences, and this phenomenon is not unique to sensory and motor systems. Here, we show that different impressions obtained through social interaction with a variety of agents uniquely modulate activity of dorsal and ventral pathways of the brain network that mediates human social behavior. We scanned brain activity with functional magnetic resonance imaging (fMRI) in 16 healthy volunteers when they performed a simple matching-pennies game with a human, human-like android, mechanical robot, interactive robot, and a computer. Before playing this game in the scanner, participants experienced social interactions with each opponent separately and scored their initial impressions using two questionnaires. We found that the participants perceived opponents in two mental dimensions: one represented “mind-holderness” in which participants attributed anthropomorphic impressions to some of the opponents that had mental functions, while the other dimension represented “mind-readerness” in which participants characterized opponents as intelligent. Interestingly, this “mind-readerness” dimension correlated to participants frequently changing their game tactic to prevent opponents from envisioning their strategy, and this was corroborated by increased entropy during the game. We also found that the two factors separately modulated activity in distinct social brain regions. Specifically, mind-holderness modulated activity in the dorsal aspect of the temporoparietal junction (TPJ) and medial prefrontal and posterior paracingulate cortices, while mind-readerness modulated activity in the ventral aspect of TPJ and the temporal pole. These results clearly demonstrate that activity in social brain networks is modulated through pre-scanning experiences of social interaction with a variety of agents. Furthermore, our findings elucidated the existence of two distinct functional networks in the social human brain. Social interaction with anthropomorphic or intelligent-looking agents may distinctly shape the internal representation of our social brain, which may in turn determine how we behave for various agents that we encounter in our society.
    Cortex 09/2014; · 6.16 Impact Factor
  • Eiichi Naito, Tomoyo Morita
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    ABSTRACT: Abstract The human brain processes every sensation evoked by altered posture and builds up a constantly changing postural model of the body. This is called a body schema, and somatic signals originating from skeletal muscles and joints, i.e. proprioceptive signals, largely contribute its formation. Recent neuroimaging techniques have revealed neuronal substrates for human body schema. A dynamic limb position model seems to be computed in the central motor network (represented by the primary motor cortex). Here, proprioceptive (kinesthetic) signals from muscle spindles are transformed into motor commands, which may underlie somatic perception of limb movement and facilitate its efficient motor control. Somatic signals originating from different body parts are integrated in the course of hierarchical somatosensory processing, and activity in higher-order somatosensory parietal cortices is capable of representing a postural model of the entire body. The left fronto-parietal network associates internal motor representation with external object representation, allowing the embodiment of external objects. In contrast, the right fronto-parietal regions connected by the most inferior branch of superior longitudinal fasciculus fibers seem to have the functions of monitoring bodily states and updating body schema. We hypothesize that activity in these right-sided fronto-parietal regions is deeply involved in corporeal self-consciousness.
    Brain and nerve = Shinkei kenkyū no shinpo 04/2014; 66(4):367-80.
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    Eiichi Naito, Satoshi Hirose
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    ABSTRACT: How very long-term (over many years) motor skill training shapes internal motor representation remains poorly understood. We provide valuable evidence that the football brain of Neymar da Silva Santos Júnior (the Brasilian footballer) recruits very limited neural resources in the motor-cortical foot regions during foot movements. We scanned his brain activity with a 3-tesla functional magnetic resonance imaging (fMRI) while he rotated his right ankle at 1 Hz. We also scanned brain activity when three other age-controlled professional footballers, two top-athlete swimmers and one amateur footballer performed the identical task. A comparison was made between Neymar's brain activity with that obtained from the others. We found activations in the left medial-wall foot motor regions during the foot movements consistently across all participants. However, the size and intensity of medial-wall activity was smaller in the four professional footballers than in the three other participants, despite no difference in amount of foot movement. Surprisingly, the reduced recruitment of medial-wall foot motor regions became apparent in Neymar. His medial-wall activity was smallest among all participants with absolutely no difference in amount of foot movement. Neymar may efficiently control given foot movements probably by largely conserving motor-cortical neural resources. We discuss this possibility in terms of over-years motor skill training effect, use-dependent plasticity, and efficient motor control.
    Frontiers in Human Neuroscience 01/2014; 8:594. · 2.91 Impact Factor
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    ABSTRACT: When confronted with complex visual scenes in daily life, how do we know which visual information represents our own hand? We investigated the cues used to assign visual information to one's own hand. Wrist tendon vibration elicits an illusory sensation of wrist movement. The intensity of this illusion attenuates when the actual motionless hand is visually presented. Testing what kind of visual stimuli attenuate this illusion will elucidate factors contributing to visual detection of one's own hand. The illusion was reduced when a stationary object was shown, but only when participants knew it was controllable with their hands. In contrast, the visual image of their own hand attenuated the illusion even when participants knew that it was not controllable. We suggest that long-term knowledge about the appearance of the body and short-term knowledge about controllability of a visual object are combined to robustly extract our own body from a visual scene.
    Proceedings of the Royal Society B: Biological Sciences 05/2012; 279(1742):3476-81. · 5.68 Impact Factor
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    Journal of Behavioral and Brain Science 01/2012; 2:343-356.
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    ABSTRACT: Considerable progress has been made in developing models of cerebellar function in sensorimotor control, as well as in identifying key problems that are the focus of current investigation. In this consensus paper, we discuss the literature on the role of the cerebellar circuitry in motor control, bringing together a range of different viewpoints. The following topics are covered: oculomotor control, classical conditioning (evidence in animals and in humans), cerebellar control of motor speech, control of grip forces, control of voluntary limb movements, timing, sensorimotor synchronization, control of corticomotor excitability, control of movement-related sensory data acquisition, cerebro-cerebellar interaction in visuokinesthetic perception of hand movement, functional neuroimaging studies, and magnetoencephalographic mapping of cortico-cerebellar dynamics. While the field has yet to reach a consensus on the precise role played by the cerebellum in movement control, the literature has witnessed the emergence of broad proposals that address cerebellar function at multiple levels of analysis. This paper highlights the diversity of current opinion, providing a framework for debate and discussion on the role of this quintessential vertebrate structure.
    The Cerebellum 12/2011; 11(2):457-87. · 2.60 Impact Factor
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    ABSTRACT: Prompted by our neuroimaging findings in 60 normal people, we examined whether focal damage to the hand section of precentral motor regions impairs hand kinesthesia in a patient, and investigated brain regions related to recovery of kinesthetic function. The damage impaired contralateral kinesthesia. The peri-lesional cerebral motor region, together with the ipsilateral intermediate cerebellum, participated in the recovered kinesthetic processing. The study confirmed the importance of precentral motor regions in human kinesthesia, and indicated a contribution of the peri-lesional cerebral region in recovered kinesthesia after precentral damage, which conceptually fits with cases of recovery of motor function.
    Neurocase 03/2011; 17(2):133-47. · 1.05 Impact Factor
  • Satoshi Hirose, Isao Nambu, Eiichi Naito
    Neuroscience Research - NEUROSCI RES. 01/2011; 71.
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    ABSTRACT: Procedural motor learning includes a period when no substantial gain in performance improvement is obtained even with repeated, daily practice. Prompted by the potential benefit of high-frequency transcutaneous electrical stimulation, we examined if the stimulation to the hand reduces redundant motor activity that likely exists in an acquired hand motor skill, so as to further upgrade stable motor performance. Healthy participants were trained until their motor performance of continuously rotating two balls in the palm of their right hand became stable. In the series of experiments, they repeated a trial performing this cyclic rotation as many times as possible in 15 s. In trials where we applied the stimulation to the relaxed thumb before they initiated the task, most reported that their movements became smoother and they could perform the movements at a higher cycle compared to the control trials. This was not possible when the dorsal side of the wrist was stimulated. The performance improvement was associated with reduction of amplitude of finger displacement, which was consistently observed irrespective of the task demands. Importantly, this kinematic change occurred without being noticed by the participants, and their intentional changes of motor strategies (reducing amplitude of finger displacement) never improved the performance. Moreover, the performance never spontaneously improved during one-week training without stimulation, whereas the improvement in association with stimulation was consistently observed across days during training on another week combined with the stimulation. The improved effect obtained in stimulation trials on one day partially carried over to the next day, thereby promoting daily improvement of plateaued performance, which could not be unlocked by the first-week intensive training. This study demonstrated the possibility of effectively improving a plateaued motor skill, and pre-movement somatic stimulation driving this behavioral change.
    PLoS ONE 01/2011; 6(10):e25670. · 3.53 Impact Factor
  • Neuroscience Research - NEUROSCI RES. 01/2011; 71.
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    Yoshinori Yamakawa, Eiichi Naito
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    ABSTRACT: Our results demonstrate that neuronal activity in the human parietal cortex, which is involved in the spatial processing of self-referential physical distance, seems to be associated with the evaluation of social distance between self and others. Thus, our neuroimaging finding raises a possibility that the human parietal cortex may have social-cognitive function
    Cognitive Maps, 01/2010; , ISBN: 978-953-307-044-5
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    ABSTRACT: Humans can judge whether an object is graspable or not by merely glancing at it. This judgment is possible because of the brain's pragmatic function that links action with perception, i.e., the spatial property of the object is immediately associated with the motor capability of hands. In this study, we investigated the neural correlates of this cognitive-motor process by conducting an event-related functional magnetic resonance imaging experiment. Healthy right-handed participants were made to judge whether they could grasp visually presented objects with their right hand without generating any actual movements [motor evaluation (ME) task]. Objects of various sizes were presented to the participants in front of their hands; they judged the graspability of the object as soon as possible. For the control, the participants simply compared the size of the presented object and the static size of their fists [size comparison (SC) task]. Thus, only in the former task, the participants had to evaluate their motor capability by briefly simulating their range of hand motion. Rostral parts of the dorsal premotor cortices (prePMd) were activated bilaterally only during the ME task, and the activities were positively correlated with the duration of the evaluation. The prePMd participates in the judgment of graspability for external objects by evaluating hand motor capability. This function may assure a basic premise for the selection of an appropriate motor option when our hands interact with a variety of external objects.
    Brain research 12/2009; 1313:134-42. · 2.46 Impact Factor
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    ABSTRACT: We examined whether visual information on the dynamic aspect of the actions performed by an individual can influence an observer's action. Sixteen participants cyclically generated an isometric precision grip force with their right thumb and index finger in synchronization with the contraction (in-phase) or relaxation phase of an experimenter's hand, foot, and mouth movements presented in videos. Visual information of the hand action significantly enhanced the observer's grip force, and this enhancement exclusively occurred during the in-phase condition. These results suggest that the effector matching between the observed and the performed actions and the temporal coincidence in the movement phase are the key factors when visual information on the dynamics of the action of an individual influences the observer's action.
    Neuroreport 09/2009; 20(16):1477-80. · 1.40 Impact Factor
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    ABSTRACT: Near-infrared spectroscopy (NIRS) has recently been used to measure human motor-cortical activation, enabling the classification of the content of a sensory-motor event such as whether the left or right hand was used. Here, we advance this NIRS application by demonstrating quantitative estimates of multiple sensory-motor events from single-trial NIRS signals. It is known that different degrees of sensory-motor activation are required to generate various hand/finger force levels. Thus, using a sparse linear regression method, we examined whether the temporal changes in different force levels could be reconstructed from NIRS signals. We measured the relative changes in oxyhemoglobin concentrations in the bilateral sensory-motor cortices while participants performed an isometric finger-pinch force production with their thumb and index finger by repeatedly exerting one of three target forces (25, 50, or 75% of the maximum voluntary contraction) for 12 s. To reconstruct the generated forces, we determined the regression parameters from the training datasets and applied these parameters to new test datasets to validate the parameters in the single-trial reconstruction. The temporal changes in the three different levels of generated forces, as well as the baseline resting state, could be reconstructed, even for the test datasets. The best reconstruction was achieved when using only the selected NIRS channels dominantly located in the contralateral sensory-motor cortex, and with a four second hemodynamic delay. These data demonstrate the potential for reconstructing different levels of external loads (forces) from those of the internal loads (activation) in the human brain using NIRS.
    NeuroImage 05/2009; 47(2):628-37. · 6.25 Impact Factor
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    ABSTRACT: Across cultures, social relationships are often thought of, described, and acted out in terms of physical space (e.g. "close friends" "high lord"). Does this cognitive mapping of social concepts arise from shared brain resources for processing social and physical relationships? Using fMRI, we found that the tasks of evaluating social compatibility and of evaluating physical distances engage a common brain substrate in the parietal cortex. The present study shows the possibility of an analytic brain mechanism to process and represent complex networks of social relationships. Given parietal cortex's known role in constructing egocentric maps of physical space, our present findings may help to explain the linguistic, psychological and behavioural links between social and physical space.
    PLoS ONE 02/2009; 4(2):e4360. · 3.53 Impact Factor
  • Eiichi Naito, Shintaro Uehara
    Neuroscience Research - NEUROSCI RES. 01/2009; 65.
  • Neuroscience Research 01/2009; 65. · 2.20 Impact Factor
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    ABSTRACT: We used functional magnetic resonance imaging (fMRI) to identify brain areas involved in auditory rhythm perception. Participants listened to three rhythm sequences that varied in temporal predictability. The most predictable sequence was an isochronous rhythm sequence of a single interval (ISO). The other two sequences had nine intervals with unequal durations. One of these had interval durations of integer ratios relative to the shortest interval (METRIC). The other had interval durations of non-integer ratios relative to the shortest interval (NON-METRIC), and was thus perceptually more complex than the other two. In addition, we presented unpredictable sequences with randomly distributed intervals (RAN). We tested two hypotheses. Firstly, that areas involved in motor timing control would also process the temporal predictability of sensory cues. Therefore, there was no active task included in the experiment that could influence the participant perception or induce motor preparation. We found that dorsal premotor cortex (PMD), SMA, preSMA, and lateral cerebellum were more active when participants listen to rhythm sequences compared to random sequences. The activity pattern in supplementary motor area (SMA) and preSMA suggested a modulation dependent on sequence predictability, strongly suggesting a role in temporal sensory prediction. Secondly, we hypothesized that the more complex the rhythm sequence, the more it would engage short-term memory processes of the prefrontal cortex. We found that the superior prefrontal cortex was more active when listening to METRIC and NON-METRIC compared to ISO. We argue that the complexity of rhythm sequences is an important factor in modulating activity in many of the rhythm areas. However, the difference in complexity of our stimuli should be regarded as continuous.
    Cortex 11/2008; 45(1):62-71. · 6.04 Impact Factor
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    ABSTRACT: Combination of visual and kinesthetic information is essential to perceive bodily movements. We conducted behavioral and functional magnetic resonance imaging experiments to investigate the neuronal correlates of visuokinesthetic combination in perception of hand movement. Participants experienced illusory flexion movement of their hand elicited by tendon vibration while they viewed video-recorded flexion (congruent: CONG) or extension (incongruent: INCONG) motions of their hand. The amount of illusory experience was graded by the visual velocities only when visual information regarding hand motion was concordant with kinesthetic information (CONG). The left posterolateral cerebellum was specifically recruited under the CONG, and this left cerebellar activation was consistent for both left and right hands. The left cerebellar activity reflected the participants' intensity of illusory hand movement under the CONG, and we further showed that coupling of activity between the left cerebellum and the "right" parietal cortex emerges during this visuokinesthetic combination/perception. The "left" cerebellum, working with the anatomically connected high-order bodily region of the "right" parietal cortex, participates in online combination of exteroceptive (vision) and interoceptive (kinesthesia) information to perceive hand movement. The cerebro-cerebellar interaction may underlie updating of one's "body image," when perceiving bodily movement from visual and kinesthetic information.
    Cerebral Cortex 06/2008; 19(1):176-86. · 8.31 Impact Factor

Publication Stats

2k Citations
239.41 Total Impact Points


  • 2011–2014
    • National Institute of Information and Communications Technology
      • Bio ICT Laboratory
      Edo, Tōkyō, Japan
    • Advanced Scientific Technology & Management Research Institute of Kyoto
      Kioto, Kyōto, Japan
  • 2012
    • UCL Eastman Dental Institute
      Londinium, England, United Kingdom
  • 2007–2009
    • Advanced Telecommunications Research Institute
      Kioto, Kyōto, Japan
  • 1994–2009
    • Kyoto University
      • • Graduate School of Informatics
      • • Graduate School of Human and Environmental Studies
      Kyoto, Kyoto-fu, Japan
  • 2008
    • Shandong Information and Communication Technology Research Institute
      Chi-nan-shih, Shandong Sheng, China
  • 2006–2008
    • University College London
      • • Institute of Neurology
      • • Wellcome Department of Imaging Neuroscience
      London, ENG, United Kingdom
  • 1999–2006
    • Karolinska Institutet
      • Institutionen för neurovetenskap
      Solna, Stockholm, Sweden
  • 2004
    • Gifu University Hospital
      Gihu, Gifu, Japan