Tetsuo Kida - Academia.edu (original) (raw)

Papers by Tetsuo Kida

Frontiers in Human Neuroscience, Nov 28, 2023

Frontiers in Human Neuroscience, Oct 31, 2023

Japanese Journal of Physical Fitness and Sports Medicine, 2003


Brain Stimulation, Jul 1, 2008

Objective: Paired-associative stimulation (PAS), which involves the combination of electrical med... more Objective: Paired-associative stimulation (PAS), which involves the combination of electrical median nerve stimulation with transcranial magnetic stimulation (TMS) over the motor cortex (M1), produces the long-term potentiation/depression (LTP/LTD)-like phenomena in the M1. The purpose of this study was to investigate the relationships between vascular responses to neuronal activities and the cortical plasticity in the M1 after PAS using near-infrared spectroscopy (NIRS). Method: Total 40 healthy volunteers were enrolled. The interstimulus intervals between median nerve stimulation and TMS over the motor cortex (M1) were 25 ms (PAS25), 10 ms (PAS10), and 100 ms (PAS100), respectively. Sham stimulation was also performed. Vascular responses in the left M1 were measured during repetitive right thumb abduction (2 Hz, 30 seconds) using NIRS before and after above interventions. In addition, the motor-evoked potential (MEP) of the abductor pollicis brevis (APB) muscle was examined before and after those interventions. Result: All subjects performed the fixed motor task in exactly the same way before and after the interventions. A significant increment in oxygenated hemoglobin (oxy-Hb) and a significant decrement in deoxygenated hemoglobin (deoxy-Hb) in the M1 were obtained during a motor task. Although the MEP amplitude of the APB muscle increased significantly after PAS25 (Fig. 1), motor task-related oxy-Hb increment after PAS25 was reduced significantly compared with those before PAS25 (Fig. 2). On the other hand, the MEP amplitude was reduced (Fig. 1), but motor task-related oxy-Hb increment and task-related deoxy-Hb decrement were enlarged significantly after PAS10 session (Figs. 2,3). There were neither significant differences in motor task-related Hb changes nor the MEP changes before and after PAS100, sham stimulation (Figs. 1-3). Conclusion: There were reciprocal relationships between the cortical plasticity and motor task-related vascular responses in the M1 under the LTP/LTD-like phenomena by PAS25/10. The contribution of the M1 to the motor output was facilitated/weakened after PAS25/10, and as a result, oxygenated blood sufficient to perform the fixed motor task was reduced/risen after PAS25/10. These phenomena reflected homeostatic plasticity in the M1 cortex.

Scientific Reports

We investigated the emotion perception process based on hospitality expertise. Forty subjects wer... more We investigated the emotion perception process based on hospitality expertise. Forty subjects were divided into the OMOTENASHI group working at inns considered to represent the spirit of hospitality, OMOTENASHI in Japan, and CONTROL group without experience in the hospitality industry. We presented neutral, happy, and angry faces to investigate P100 and N170 by these faces, and psychophysical changes by the favor rating test to evaluate emotional perception. In the favor rating test, the score was significantly smaller (less favorable) in OMOTENASHI than in CONTROL. Regarding event-related potential components, the maximum amplitude of P100 was significantly larger for a neutral face at the right occipital electrode in OMOTENASHI than in CONTROL, and it was significantly larger for an angry face at both occipital electrodes in OMOTENASHI than in CONTROL. However, the peak latency and maximum amplitude of N170 were not significantly different between OMOTENASHI and CONTROL at both te...

Japanese Journal of Physical Fitness and Sports Medicine, 2003

Advances in Exercise and Sports Physiology, Dec 1, 2001

Previous studies have demonstrated centrifugal modulation of somatosensory cortical responses bef... more Previous studies have demonstrated centrifugal modulation of somatosensory cortical responses before the onset of self-initiated or externally-initiated voluntary movement. To elucidate the centrifugal regulation just before an imperative signal initiating a movement, we examined changes in short- and long-latency somatosensory evoked potentials (SEPs) just before an imperative signal in a forewarned reaction time task. Twelve healthy adults participated in this study. An auditory warning signal was followed 2 s later by a visual imperative signal. An electrical stimulus to elicit SEPs was presented to the right median nerve 200 ms before the imperative signal. The subjects were instructed to extend the right second digit when the visual stimulus was presented (reaction condition), to silently count the number of visual stimuli (visual attention condition), or to silently count the number of the electrical stimuli (somatosensory attention condition). The control condition involved n...

NeuroImage, Jan 15, 2009

We recorded cortical activities in response to the onset and offset of a train of electrical puls... more We recorded cortical activities in response to the onset and offset of a train of electrical pulses applied to the right hand in eleven healthy volunteers by the use of magnetoencephalograms to clarify temporal and spatial profiles of the somatosensory on- and off-cortical responses. Results showed that a region around the upper bank of the sylvian fissure of both hemispheres responded to the onset and offset of the stimulus, while the activity in the primary somatosensory cortex (SI) of the hemisphere contralateral to the stimulation was clear only for the onset response. The SI activity consisted of two components suggesting that two distinct populations of neurons in SI were involved in processing a train of pulses. The location of the source of activity in the contralateral para-sylvian region (cPara) differed significantly between the on- and off-response, while that of the activity in the ipsilateral para-sylvian region (iPara) did not. The differences in location of the cPara...

Brain research. Cognitive brain research, 2004

The modulation of the somatosensory N140 was examined in a selective attention task where a contr... more The modulation of the somatosensory N140 was examined in a selective attention task where a control condition was applied and the interstimulus interval (ISI) was varied. Electrical stimuli were randomly presented to the left index (p=0.4) and middle fingers (p=0.1), and right index (p=0.4) and middle fingers (p=0.1). In the attend-right condition, subjects were instructed to count silently the number of infrequent target stimuli presented to the right middle finger, and to the left middle finger in the attend-left condition. They had no task in the control condition. Each condition was performed with two different sets of ISI (mean 400 vs. 800 ms). The somatosensory N140 elicited by frequent standard stimuli was analyzed. The N140 amplitude was larger for the attended ERP compared to the control and unattended ERPs. This attention effect was more marked at the frontal electrodes compared to the temporal electrodes contralateral to the stimulation side. Furthermore, the attention ef...

Neuroscience Research, 2009

Electrical stimulation applied to visual cortex is known to evoke phosphen in blind patient, indi... more Electrical stimulation applied to visual cortex is known to evoke phosphen in blind patient, indicating a possibility of cortical implant. However, it is not well understood how electrical stimulation activates cortical neuronal circuits. We investigated the spatiotemporal properties of electrically induced response in mouse primary visual cortex (V1) using voltage-sensitive dye. A biphasic current stimulation was delivered to layer 4 of V1 by glass microelectrode. Stimulation (> 40 A) to layer 4 induced response around the electrode and spread laterally to nearby area. The amplitude and the area of response became larger as the stimulation current and the response was recorded occasionally in latero-medial area. Electrical stimulation on the superficial layer (layer 1) was less effective. Stimulation on deeper layers (layers 4 and 5) induced the larger and more widely spreading activity that was followed by a slow negative response, possibly corresponds to hyperpolarization of cells.

Experimental Brain Research, 2007

We investigated the eVect of deviant stimulus probability on the somatosensory magnetic mismatch ... more We investigated the eVect of deviant stimulus probability on the somatosensory magnetic mismatch negativity (MMNm) using an electrical two-point stimulation. First, we determined the discrimination threshold (DT) of the two-point distance. We applied standard stimuli at a distance that subjects felt as one point and deviant stimuli at a distance that subjects deWnitely felt as two points. We used three deviant stimulus probabilities, 10, 30, and 50%. The components peaking around 30-70 ms (Wrst component) and 150-250 ms (fourth component) following deviant stimuli were signiWcantly larger than those following standard stimuli in 10% condition, but not in 30 or 50% condition. The equivalent current dipole (ECD) was located in the contralateral primary somatosensory cortex (cSI) for the Wrst component, and in the cSI and in the contralateral secondary somatosensory cortex (cSII) for the fourth component. The peak amplitude of the MMNm decreased as the probability of the deviant stimulus increased. The Somatosensory MMNm was aVected by deviant stimulus probability similar to an auditory mismatch negativity (MMN).

Experimental Brain Research, 2009

We developed a visual 3D model of a space module and analyzed whether activity in the auditory co... more We developed a visual 3D model of a space module and analyzed whether activity in the auditory cortex is influenced by rotating the image using magnetoencephalography. We presented 1,000 Hz pure tone as an auditory stimulus in four different visual conditions: (1) RR: a virtual image rotated around the center, (2) VR: images rotated vertically, (3) HR: images rotated horizontally and (4) ST: the images did not rotate. We compared the difference in the auditory evoked component among the conditions. The dipoles were estimated to lie in Heschl's gyrus. The dipole moment was significantly larger for RR and VR than for ST in the right hemisphere. Investigating the inter-hemispheric differences in each visual condition, the dipole moments for RR and VR were significantly larger in the right hemisphere than the left hemisphere. Auditory activity was influenced by visual movement inducing self-motion perception and the effect of such visual movement on the auditory cortex was right-dominant.

Experimental Brain Research, 2008

Quick detection of changes in the sensory environment is very important for survival, resulting i... more Quick detection of changes in the sensory environment is very important for survival, resulting in automatic shifts of attention to the event and the facilitation of subsequent processes to execute appropriate behaviors. The abrupt onset or oVset of a sensory stimulus should also activate the neural network detecting changes. To test this hypothesis, we compared cortical on-and oV-responses using somatosensory-evoked potentials (SEPs) elicited by a train of electrical pulses delivered to the right hand in eight healthy volunteers. SEPs were recorded from 15 electrodes on the scalp at three diVerent interstimulus intervals (ISIs, 50, 20, and 10 ms) under two sets of conditions (attended and unattended). Both the onset and oVset of stimulation evoked two similar components, P100 and N140, in the attended and unattended conditions. The latency of P100 and N140 in response to stimulus onset did not diVer among the three ISIs, while the latency of both components in response to stimulus oVset was signiWcantly longer for the longer ISI; that is, detection of the cessation of the stimulation was based on short-term memory of the stimulus frequency. The present results supported a cortical network triggered by both the onset and oVset of sensory stimulation. In this network, the change is automatically detected using a memory trace by comparing the abrupt event (on or oV) with the preceding condition (silent or repetitive stimuli).

European Journal of Neuroscience, 2009

We recorded cortical activities in response to the onset and offset of a pure tone of long durati... more We recorded cortical activities in response to the onset and offset of a pure tone of long duration (LONG) and a train of brief pulses of a pure tone with an interstimulus interval of 50 ms (ISI-50 ms) or 100 ms (ISI-100 ms) by use of magnetoencephalograms in 11 healthy volunteers to clarify temporal and spatial profiles of the auditory on- and off-cortical response. Results showed that a region around the superior temporal gyrus (STG) of both hemispheres responded to both the onset and offset of the stimulus. The location of the source responsible for the main activity (N1m) was not significantly different between the on- and off-responses for any of the three tones. The peak latency of on-N1m was similar under the three conditions, while the peak latency of off-N1m was precisely determined by the ISI, which suggested that off-N1m is based on short-term memory of the stimulus frequency. In addition, there was a positive correlation of the N1m amplitude of N1m between the on- and off-responses among the subjects. The present results suggested that auditory on-N1m and off-N1m have similar physiological significance involved in responding to abrupt changes.

The Journal of Physical Fitness and Sports Medicine, 2017

Effective behaviors optimized for various situations are enabled by various sensory information. ... more Effective behaviors optimized for various situations are enabled by various sensory information. How does the brain deal simultaneously with information from different sensory systems? Investigation of multisensory processing began from neuroanatomical and neurophysiological studies at the level of single neurons. Accumulation of knowledge concerning neurons and progress in recording techniques of human brain activity have led to a massive expansion in recent neuroscientific studies using various combinations of brain activity recording and cognitive tasks. In this paper, we briefly review recent neuroscientific studies related to multisensory convergence and interaction, focusing on electrophysiological and imaging studies in humans.

Frontiers in Human Neuroscience, 2016

Magnetoencephalography (MEG) and electroencephalography (EEG) are invaluable neuroscientific tool... more Magnetoencephalography (MEG) and electroencephalography (EEG) are invaluable neuroscientific tools for unveiling human neural dynamics in three dimensions (space, time, and frequency), which are associated with a wide variety of perceptions, cognition, and actions. MEG/EEG also provides different categories of neuronal indices including activity magnitude, connectivity, and network properties along the three dimensions. In the last 20 years, interest has increased in interregional connectivity and complex network properties assessed by various sophisticated scientific analyses. We herein review the definition, computation, short history, and pros and cons of connectivity and complex network (graph-theory) analyses applied to MEG/EEG signals. We briefly describe recent developments in source reconstruction algorithms essential for source-space connectivity and network analyses. Furthermore, we discuss a relatively novel approach used in MEG/EEG studies to examine the complex dynamics represented by human brain activity. The correct and effective use of these neuronal metrics provides a new insight into the multi-dimensional dynamics of the neural representations of various functions in the complex human brain.

PLoS ONE, 2013

Previous studies have demonstrated task-related changes in brain activation and interregional con... more Previous studies have demonstrated task-related changes in brain activation and interregional connectivity but the temporal dynamics of functional properties of the brain during task execution is still unclear. In the present study, we investigated task-related changes in functional properties of the human brain network by applying graph-theoretical analysis to magnetoencephalography (MEG). Subjects performed a cue-target attention task in which a visual cue informed them of the direction of focus for incoming auditory or tactile target stimuli, but not the sensory modality. We analyzed the MEG signal in the cue-target interval to examine network properties during attentional control. Cluster-based nonparametric permutation tests with the Monte-Carlo method showed that in the cue-target interval, beta activity was desynchronized in the sensori-motor region including premotor and posterior parietal regions in the hemisphere contralateral to the attended side. Graph-theoretical analysis revealed that, in beta frequency, global hubs were found around the sensori-motor and prefrontal regions, and functional segregation over the entire network was decreased during attentional control compared to the baseline. Thus, network measures revealed task-related temporal changes in functional properties of the human brain network, leading to the understanding of how the brain dynamically responds to task execution as a network.

Journal of Neurophysiology, 2007

The neural mechanisms underlying unimodal spatial attention have long been studied, but the corti... more The neural mechanisms underlying unimodal spatial attention have long been studied, but the cortical processes underlying cross-modal links remain a matter of debate. To reveal the cortical processes underlying the cross-modal links between vision and touch in spatial attention, we recorded magnetoencephalographic (MEG) responses to electrocutaneous stimuli when subjects directed attention to an electrocutaneous or visual stimulus presented randomly in the left or right space. Neural responses recorded around the bilateral sylvian fissures at 85 and 100 ms after the electrocutaneous stimulus were significantly enhanced by spatial attention in both the touch-irrelevant and -relevant modalities. Source analysis revealed that the sylvian responses were generated in the secondary somatosensory cortex (SII). An early response, M50c, generated in the contralateral primary somatosensory cortex (SI), was not modulated by attention. There were no significant attentional changes in the source...

Journal of Neurophysiology, 2011

Numerous studies have demonstrated effects of spatial attention within single sensory modalities ... more Numerous studies have demonstrated effects of spatial attention within single sensory modalities (within-modal spatial attention) and the effect of directing attention to one sense compared with the other senses (intermodal attention) on cortical neuronal activity. Furthermore, recent studies have been revealing that the effects of spatial attention directed to a certain location in a certain sense spread to the other senses at the same location in space (cross-modal spatial attention). The present study used magnetoencephalography to examine the temporal dynamics of the effects of within-modal and cross-modal spatial and intermodal attention on cortical processes responsive to visual stimuli. Visual or tactile stimuli were randomly presented on the left or right side at a random interstimulus interval and subjects directed attention to the left or right when vision or touch was a task-relevant modality. Sensor-space analysis showed that a response around the occipitotemporal region...

Frontiers in Human Neuroscience, Nov 28, 2023

Frontiers in Human Neuroscience, Oct 31, 2023

Japanese Journal of Physical Fitness and Sports Medicine, 2003


Brain Stimulation, Jul 1, 2008

Objective: Paired-associative stimulation (PAS), which involves the combination of electrical med... more Objective: Paired-associative stimulation (PAS), which involves the combination of electrical median nerve stimulation with transcranial magnetic stimulation (TMS) over the motor cortex (M1), produces the long-term potentiation/depression (LTP/LTD)-like phenomena in the M1. The purpose of this study was to investigate the relationships between vascular responses to neuronal activities and the cortical plasticity in the M1 after PAS using near-infrared spectroscopy (NIRS). Method: Total 40 healthy volunteers were enrolled. The interstimulus intervals between median nerve stimulation and TMS over the motor cortex (M1) were 25 ms (PAS25), 10 ms (PAS10), and 100 ms (PAS100), respectively. Sham stimulation was also performed. Vascular responses in the left M1 were measured during repetitive right thumb abduction (2 Hz, 30 seconds) using NIRS before and after above interventions. In addition, the motor-evoked potential (MEP) of the abductor pollicis brevis (APB) muscle was examined before and after those interventions. Result: All subjects performed the fixed motor task in exactly the same way before and after the interventions. A significant increment in oxygenated hemoglobin (oxy-Hb) and a significant decrement in deoxygenated hemoglobin (deoxy-Hb) in the M1 were obtained during a motor task. Although the MEP amplitude of the APB muscle increased significantly after PAS25 (Fig. 1), motor task-related oxy-Hb increment after PAS25 was reduced significantly compared with those before PAS25 (Fig. 2). On the other hand, the MEP amplitude was reduced (Fig. 1), but motor task-related oxy-Hb increment and task-related deoxy-Hb decrement were enlarged significantly after PAS10 session (Figs. 2,3). There were neither significant differences in motor task-related Hb changes nor the MEP changes before and after PAS100, sham stimulation (Figs. 1-3). Conclusion: There were reciprocal relationships between the cortical plasticity and motor task-related vascular responses in the M1 under the LTP/LTD-like phenomena by PAS25/10. The contribution of the M1 to the motor output was facilitated/weakened after PAS25/10, and as a result, oxygenated blood sufficient to perform the fixed motor task was reduced/risen after PAS25/10. These phenomena reflected homeostatic plasticity in the M1 cortex.

Scientific Reports

We investigated the emotion perception process based on hospitality expertise. Forty subjects wer... more We investigated the emotion perception process based on hospitality expertise. Forty subjects were divided into the OMOTENASHI group working at inns considered to represent the spirit of hospitality, OMOTENASHI in Japan, and CONTROL group without experience in the hospitality industry. We presented neutral, happy, and angry faces to investigate P100 and N170 by these faces, and psychophysical changes by the favor rating test to evaluate emotional perception. In the favor rating test, the score was significantly smaller (less favorable) in OMOTENASHI than in CONTROL. Regarding event-related potential components, the maximum amplitude of P100 was significantly larger for a neutral face at the right occipital electrode in OMOTENASHI than in CONTROL, and it was significantly larger for an angry face at both occipital electrodes in OMOTENASHI than in CONTROL. However, the peak latency and maximum amplitude of N170 were not significantly different between OMOTENASHI and CONTROL at both te...

Japanese Journal of Physical Fitness and Sports Medicine, 2003

Advances in Exercise and Sports Physiology, Dec 1, 2001

Previous studies have demonstrated centrifugal modulation of somatosensory cortical responses bef... more Previous studies have demonstrated centrifugal modulation of somatosensory cortical responses before the onset of self-initiated or externally-initiated voluntary movement. To elucidate the centrifugal regulation just before an imperative signal initiating a movement, we examined changes in short- and long-latency somatosensory evoked potentials (SEPs) just before an imperative signal in a forewarned reaction time task. Twelve healthy adults participated in this study. An auditory warning signal was followed 2 s later by a visual imperative signal. An electrical stimulus to elicit SEPs was presented to the right median nerve 200 ms before the imperative signal. The subjects were instructed to extend the right second digit when the visual stimulus was presented (reaction condition), to silently count the number of visual stimuli (visual attention condition), or to silently count the number of the electrical stimuli (somatosensory attention condition). The control condition involved n...

NeuroImage, Jan 15, 2009

We recorded cortical activities in response to the onset and offset of a train of electrical puls... more We recorded cortical activities in response to the onset and offset of a train of electrical pulses applied to the right hand in eleven healthy volunteers by the use of magnetoencephalograms to clarify temporal and spatial profiles of the somatosensory on- and off-cortical responses. Results showed that a region around the upper bank of the sylvian fissure of both hemispheres responded to the onset and offset of the stimulus, while the activity in the primary somatosensory cortex (SI) of the hemisphere contralateral to the stimulation was clear only for the onset response. The SI activity consisted of two components suggesting that two distinct populations of neurons in SI were involved in processing a train of pulses. The location of the source of activity in the contralateral para-sylvian region (cPara) differed significantly between the on- and off-response, while that of the activity in the ipsilateral para-sylvian region (iPara) did not. The differences in location of the cPara...

Brain research. Cognitive brain research, 2004

The modulation of the somatosensory N140 was examined in a selective attention task where a contr... more The modulation of the somatosensory N140 was examined in a selective attention task where a control condition was applied and the interstimulus interval (ISI) was varied. Electrical stimuli were randomly presented to the left index (p=0.4) and middle fingers (p=0.1), and right index (p=0.4) and middle fingers (p=0.1). In the attend-right condition, subjects were instructed to count silently the number of infrequent target stimuli presented to the right middle finger, and to the left middle finger in the attend-left condition. They had no task in the control condition. Each condition was performed with two different sets of ISI (mean 400 vs. 800 ms). The somatosensory N140 elicited by frequent standard stimuli was analyzed. The N140 amplitude was larger for the attended ERP compared to the control and unattended ERPs. This attention effect was more marked at the frontal electrodes compared to the temporal electrodes contralateral to the stimulation side. Furthermore, the attention ef...

Neuroscience Research, 2009

Electrical stimulation applied to visual cortex is known to evoke phosphen in blind patient, indi... more Electrical stimulation applied to visual cortex is known to evoke phosphen in blind patient, indicating a possibility of cortical implant. However, it is not well understood how electrical stimulation activates cortical neuronal circuits. We investigated the spatiotemporal properties of electrically induced response in mouse primary visual cortex (V1) using voltage-sensitive dye. A biphasic current stimulation was delivered to layer 4 of V1 by glass microelectrode. Stimulation (> 40 A) to layer 4 induced response around the electrode and spread laterally to nearby area. The amplitude and the area of response became larger as the stimulation current and the response was recorded occasionally in latero-medial area. Electrical stimulation on the superficial layer (layer 1) was less effective. Stimulation on deeper layers (layers 4 and 5) induced the larger and more widely spreading activity that was followed by a slow negative response, possibly corresponds to hyperpolarization of cells.

Experimental Brain Research, 2007

We investigated the eVect of deviant stimulus probability on the somatosensory magnetic mismatch ... more We investigated the eVect of deviant stimulus probability on the somatosensory magnetic mismatch negativity (MMNm) using an electrical two-point stimulation. First, we determined the discrimination threshold (DT) of the two-point distance. We applied standard stimuli at a distance that subjects felt as one point and deviant stimuli at a distance that subjects deWnitely felt as two points. We used three deviant stimulus probabilities, 10, 30, and 50%. The components peaking around 30-70 ms (Wrst component) and 150-250 ms (fourth component) following deviant stimuli were signiWcantly larger than those following standard stimuli in 10% condition, but not in 30 or 50% condition. The equivalent current dipole (ECD) was located in the contralateral primary somatosensory cortex (cSI) for the Wrst component, and in the cSI and in the contralateral secondary somatosensory cortex (cSII) for the fourth component. The peak amplitude of the MMNm decreased as the probability of the deviant stimulus increased. The Somatosensory MMNm was aVected by deviant stimulus probability similar to an auditory mismatch negativity (MMN).

Experimental Brain Research, 2009

We developed a visual 3D model of a space module and analyzed whether activity in the auditory co... more We developed a visual 3D model of a space module and analyzed whether activity in the auditory cortex is influenced by rotating the image using magnetoencephalography. We presented 1,000 Hz pure tone as an auditory stimulus in four different visual conditions: (1) RR: a virtual image rotated around the center, (2) VR: images rotated vertically, (3) HR: images rotated horizontally and (4) ST: the images did not rotate. We compared the difference in the auditory evoked component among the conditions. The dipoles were estimated to lie in Heschl's gyrus. The dipole moment was significantly larger for RR and VR than for ST in the right hemisphere. Investigating the inter-hemispheric differences in each visual condition, the dipole moments for RR and VR were significantly larger in the right hemisphere than the left hemisphere. Auditory activity was influenced by visual movement inducing self-motion perception and the effect of such visual movement on the auditory cortex was right-dominant.

Experimental Brain Research, 2008

Quick detection of changes in the sensory environment is very important for survival, resulting i... more Quick detection of changes in the sensory environment is very important for survival, resulting in automatic shifts of attention to the event and the facilitation of subsequent processes to execute appropriate behaviors. The abrupt onset or oVset of a sensory stimulus should also activate the neural network detecting changes. To test this hypothesis, we compared cortical on-and oV-responses using somatosensory-evoked potentials (SEPs) elicited by a train of electrical pulses delivered to the right hand in eight healthy volunteers. SEPs were recorded from 15 electrodes on the scalp at three diVerent interstimulus intervals (ISIs, 50, 20, and 10 ms) under two sets of conditions (attended and unattended). Both the onset and oVset of stimulation evoked two similar components, P100 and N140, in the attended and unattended conditions. The latency of P100 and N140 in response to stimulus onset did not diVer among the three ISIs, while the latency of both components in response to stimulus oVset was signiWcantly longer for the longer ISI; that is, detection of the cessation of the stimulation was based on short-term memory of the stimulus frequency. The present results supported a cortical network triggered by both the onset and oVset of sensory stimulation. In this network, the change is automatically detected using a memory trace by comparing the abrupt event (on or oV) with the preceding condition (silent or repetitive stimuli).

European Journal of Neuroscience, 2009

We recorded cortical activities in response to the onset and offset of a pure tone of long durati... more We recorded cortical activities in response to the onset and offset of a pure tone of long duration (LONG) and a train of brief pulses of a pure tone with an interstimulus interval of 50 ms (ISI-50 ms) or 100 ms (ISI-100 ms) by use of magnetoencephalograms in 11 healthy volunteers to clarify temporal and spatial profiles of the auditory on- and off-cortical response. Results showed that a region around the superior temporal gyrus (STG) of both hemispheres responded to both the onset and offset of the stimulus. The location of the source responsible for the main activity (N1m) was not significantly different between the on- and off-responses for any of the three tones. The peak latency of on-N1m was similar under the three conditions, while the peak latency of off-N1m was precisely determined by the ISI, which suggested that off-N1m is based on short-term memory of the stimulus frequency. In addition, there was a positive correlation of the N1m amplitude of N1m between the on- and off-responses among the subjects. The present results suggested that auditory on-N1m and off-N1m have similar physiological significance involved in responding to abrupt changes.

The Journal of Physical Fitness and Sports Medicine, 2017

Effective behaviors optimized for various situations are enabled by various sensory information. ... more Effective behaviors optimized for various situations are enabled by various sensory information. How does the brain deal simultaneously with information from different sensory systems? Investigation of multisensory processing began from neuroanatomical and neurophysiological studies at the level of single neurons. Accumulation of knowledge concerning neurons and progress in recording techniques of human brain activity have led to a massive expansion in recent neuroscientific studies using various combinations of brain activity recording and cognitive tasks. In this paper, we briefly review recent neuroscientific studies related to multisensory convergence and interaction, focusing on electrophysiological and imaging studies in humans.

Frontiers in Human Neuroscience, 2016

Magnetoencephalography (MEG) and electroencephalography (EEG) are invaluable neuroscientific tool... more Magnetoencephalography (MEG) and electroencephalography (EEG) are invaluable neuroscientific tools for unveiling human neural dynamics in three dimensions (space, time, and frequency), which are associated with a wide variety of perceptions, cognition, and actions. MEG/EEG also provides different categories of neuronal indices including activity magnitude, connectivity, and network properties along the three dimensions. In the last 20 years, interest has increased in interregional connectivity and complex network properties assessed by various sophisticated scientific analyses. We herein review the definition, computation, short history, and pros and cons of connectivity and complex network (graph-theory) analyses applied to MEG/EEG signals. We briefly describe recent developments in source reconstruction algorithms essential for source-space connectivity and network analyses. Furthermore, we discuss a relatively novel approach used in MEG/EEG studies to examine the complex dynamics represented by human brain activity. The correct and effective use of these neuronal metrics provides a new insight into the multi-dimensional dynamics of the neural representations of various functions in the complex human brain.

PLoS ONE, 2013

Previous studies have demonstrated task-related changes in brain activation and interregional con... more Previous studies have demonstrated task-related changes in brain activation and interregional connectivity but the temporal dynamics of functional properties of the brain during task execution is still unclear. In the present study, we investigated task-related changes in functional properties of the human brain network by applying graph-theoretical analysis to magnetoencephalography (MEG). Subjects performed a cue-target attention task in which a visual cue informed them of the direction of focus for incoming auditory or tactile target stimuli, but not the sensory modality. We analyzed the MEG signal in the cue-target interval to examine network properties during attentional control. Cluster-based nonparametric permutation tests with the Monte-Carlo method showed that in the cue-target interval, beta activity was desynchronized in the sensori-motor region including premotor and posterior parietal regions in the hemisphere contralateral to the attended side. Graph-theoretical analysis revealed that, in beta frequency, global hubs were found around the sensori-motor and prefrontal regions, and functional segregation over the entire network was decreased during attentional control compared to the baseline. Thus, network measures revealed task-related temporal changes in functional properties of the human brain network, leading to the understanding of how the brain dynamically responds to task execution as a network.

Journal of Neurophysiology, 2007

The neural mechanisms underlying unimodal spatial attention have long been studied, but the corti... more The neural mechanisms underlying unimodal spatial attention have long been studied, but the cortical processes underlying cross-modal links remain a matter of debate. To reveal the cortical processes underlying the cross-modal links between vision and touch in spatial attention, we recorded magnetoencephalographic (MEG) responses to electrocutaneous stimuli when subjects directed attention to an electrocutaneous or visual stimulus presented randomly in the left or right space. Neural responses recorded around the bilateral sylvian fissures at 85 and 100 ms after the electrocutaneous stimulus were significantly enhanced by spatial attention in both the touch-irrelevant and -relevant modalities. Source analysis revealed that the sylvian responses were generated in the secondary somatosensory cortex (SII). An early response, M50c, generated in the contralateral primary somatosensory cortex (SI), was not modulated by attention. There were no significant attentional changes in the source...

Journal of Neurophysiology, 2011

Numerous studies have demonstrated effects of spatial attention within single sensory modalities ... more Numerous studies have demonstrated effects of spatial attention within single sensory modalities (within-modal spatial attention) and the effect of directing attention to one sense compared with the other senses (intermodal attention) on cortical neuronal activity. Furthermore, recent studies have been revealing that the effects of spatial attention directed to a certain location in a certain sense spread to the other senses at the same location in space (cross-modal spatial attention). The present study used magnetoencephalography to examine the temporal dynamics of the effects of within-modal and cross-modal spatial and intermodal attention on cortical processes responsive to visual stimuli. Visual or tactile stimuli were randomly presented on the left or right side at a random interstimulus interval and subjects directed attention to the left or right when vision or touch was a task-relevant modality. Sensor-space analysis showed that a response around the occipitotemporal region...