Shinobu Kohsaka - Academia.edu (original) (raw)
Papers by Shinobu Kohsaka
PubMed, Mar 1, 1990
We designed a new cassette EEG recording system which consists of a recording block (an ambulator... more We designed a new cassette EEG recording system which consists of a recording block (an ambulatory-type data recorder and a newly developed pre-amplifier) and a reproduction block (a fixed-type data recorder, a personal computer equipped with A/D converting board and an intervening EEG device for a bandpass filter). This system was applied to 36 epileptic children, and 33 ictal records were obtained. The seizure type could be precisely classified by a comparative analysis of the data computed from this system and from the ictal symptoms. Three representative cases were presented with actual analysis procedures.
Brain Research, Aug 1, 1999
Ž. Ž. Simultaneous analysis of brainstem auditory evoked potentials BAEPs with reference to elect... more Ž. Ž. Simultaneous analysis of brainstem auditory evoked potentials BAEPs with reference to electroencephalography EEG was designed to examine the brainstem function corresponding to the EEG event. With this method, we investigated the brainstem function pre-and Ž. during the paroxysmal discharge in human absence seizures classified as primary generalized epilepsy PGE. Two types of functional Ž. change in the lower brainstem were revealed as parameters of wave-III components amplitude and area of BAEPs without significant Ž change in the upper brainstem. One was long-range biphasic fluctuation acceleration followed by abrupt deceleration with the maximum. y6.4 " 3.2 s before the seizure onset , and the other was rhythmic oscillation with 3 Hz. The latter, synchronized with the cortical spike-and-wave complex, imposed on the descending slope of the former. One important point is that both preceded the onset of cortical paroxysmal discharge. The results reappraise the classical hypothesis of ''centrencephalic system'' on seizure generating mechanism in human PGE. The results prove the primary triggering role of the lower brainstem that is independent of sleep-related synchronizations. The method is applicable to other types of EEG event for the investigation of brainstem involvement.
Neuroscience, Dec 1, 2002
öThe excitability change of the brainstem was investigated before and during the conspicuous epil... more öThe excitability change of the brainstem was investigated before and during the conspicuous epileptic discharge in six patients with generalized convulsive seizures. The discharge consisted of a short duration of recruiting rhythm, which was considered equivalent to the seizure discharge on electroencephalogram. The excitability of the brainstem was measured with the parameters (amplitude and area) of component waves (wave-III and-V) of brainstem auditory evoked potentials. The theoretical background of the analysis is that brainstem auditory evoked potentials are 'far-¢eld' potentials, by which they convey the information on the activity change of the brainstem even during the paroxysmal discharge within the cortex. The excitability of both the ventral (parameters of wave-III) and the dorsal brainstem (parameters of wave-V) exhibited a synchronized change (activation^inactivation). They were enhanced from 32.4 þ 0.4 s, reaching the maxima before the onset of the seizure discharge, and decayed corresponding to the emergence of the recruiting rhythm. The results suggest the possibility that the widespread (ventral and dorsal) and synchronized activation of the brainstem triggers the seizure discharge in human generalized epilepsy. During the widespread activation of the brainstem, both the thalamus and the cortex probably undergo a suppressed inhibitory state through the cholinergic activation, precipitating the seizure discharge.
Brain & Development, Feb 1, 2015
Purpose: We evaluated whether magnetoencephalography (MEG), in addition to surgery, was valuable ... more Purpose: We evaluated whether magnetoencephalography (MEG), in addition to surgery, was valuable for the diagnosis and management of epileptic syndromes in patients with neocortical epilepsy (NE). Methods: We studied MEG in 73 patients (29 females; aged 1-26 years; mean 10.3 years) for the clinical diagnosis of epilepsy and for preoperative evaluation. MEG data were recorded by 204-channel whole head gradiometers with a 600 Hz sampling rate. MEG spike sources were localized on magnetic resonance images (MRI) using a single dipole model to project equivalent current dipoles. Results: MEG localized an epileptic focus with single clustered dipoles in 24 (33%) of 73 NE patients: 16 (25%) of 64 symptomatic localization-related epilepsy (SLRE) patients and eight (89%) of nine idiopathic localization-related epilepsy (ILRE) patients. MEG provided advantageous information in 12 (50%) of 24 patients with clustered dipoles and confirmed the diagnosis in the remaining 12 (50%). Furthermore, the use of MEG resulted in changes to surgical treatments in nine (38%) patients and in medical management in eight (33%). MEG confirmed the diagnosis in eight (16%) of 49 patients with scattered dipoles. MRI identified a single lesion (28 patients, 38%), multiple lesions (5, 7%), and no lesion (40, 55%). MRI provided confirming information in 19 of 28 patients with a single lesion and 18 of them required surgical resections. MRI did not provide any supportive information in 54 (74%) patients with a single (9), multiple (5) and no lesion (40). Conclusion: Our study shows that MEG provides fundamental information to aid the choice of diagnostic and therapeutic procedures including changes in medication in addition to surgical treatments for NE.
International Congress Series, Jun 1, 2007
This study charted the magnetoencephalographic (MEG) findings with clinical course for atypical b... more This study charted the magnetoencephalographic (MEG) findings with clinical course for atypical benign partial epilepsy in childhood (ABPE). We discuss the etiology and epileptogenesis of this condition. Three patients with ABPE (age: 8-10 years old) underwent MEG analysis using a 204ch helmetshape MEG system. MEG showed unilateral epileptic activities over the frontal and temporal operculum and insular cortex during the worst seizures. The findings changed as the seizures were reduced by localized clustering of equivalent current dipoles (ECDs) at the unilateral temporal and frontal operculum near the primary motor area. We concluded that the localizations and directions of the ECDs in our patients during seizure remission resembled those of benign Rolandic epilepsy (BRE). We suggest a similar pathogenesis for ABPE and BRE.
![Research paper thumbnail of [11C]Flumazenil Positron Emission Tomography Analyses of Brain Gamma-Aminobutyric Acid Type A Receptors in Angelman Syndrome](https://attachments.academia-assets.com/106980636/thumbnails/1.jpg)
](The Journal of Pediatrics, Apr 1, 2008
Objective To evaluate the role of the gamma-aminobutyric acid type A (GABA A) receptor in Angelma... more Objective To evaluate the role of the gamma-aminobutyric acid type A (GABA A) receptor in Angelman syndrome (AS). Study design We performed [ 11 C]flumazenil positron emission tomography (PET) and examined GABA A receptor expression in 7 patients with AS of various genotypes (5 with the deletion, 1 with an imprinting defect [ID], and 1 with a UBE3A mutation) and 4 normal control healthy volunteers. Results Relative to the control subjects, the [ 11 C]flumazenil binding potentials (BPs) were significantly higher in the cerebral cortex and cerebellum in the 5 patients with the deletion and in the 1 patient with a UBE3A mutation, and were less frequently or barely increased in adult patients with the deletion and in the patient with IDs. Conclusions Total GABA A receptor expression was increased in patients with AS with various genotypes. We suggest that a developmental dysregulation of the GABA A receptor subunits occurs in patients with AS.
Clinical Neurophysiology, Oct 1, 2019
The results indicate that the absence of basic rhythm suggests delirium. The slowing of basic rhy... more The results indicate that the absence of basic rhythm suggests delirium. The slowing of basic rhythm and the absence of basic rhythm attenuation during the eyes-open state were found in the patients with dementia and psychosis, respectively. Normal EEG pattern was observed in depressed patients. The total ICDSC scores in these confused patients were high regardless of the differences in EEG patterns. It would be beneficial to use EEG power spectrum to understand the pathophysiology of confused patients to enable the appropriate treatment.
Clinical Neurophysiology, Oct 1, 2010
Neuroscience, 2012
A K-complex (KC) in the electroencephalographs (EEGs) indicates a moderate depth of slow-wave sle... more A K-complex (KC) in the electroencephalographs (EEGs) indicates a moderate depth of slow-wave sleep (SWS) in humans and animals. The cortical activities are upregulated during the periods between the KCs ("up state"), and it is proposed that temporarily stored memories during wakeful periods will be consolidated during these periods. Although the underlying mechanism for KCs is proposed to be in the cortex itself, the involvement of the brainstem has not been explored. Here we investigate the excitability changes of the brainstem preceding, during, and after KCs in humans. We simultaneously recorded brainstem auditory evoked potentials (BAEPs) with EEGs, and sequentially analyzed BAEPs around the KCs. The results showed a transient activation of the ventral brainstem preceding the KC and a sustained activation of the dorsal brainstem outlasting the KC. Thus, it is suggested that KCs are triggered by the activation of the brainstem and that the "up state" is maintained by the sustained activation of the brainstem.
Brain & Development, Jul 1, 1992
A 9-year-old female MELAS patient with myoclonus is reported, with emphasis on the results of ele... more A 9-year-old female MELAS patient with myoclonus is reported, with emphasis on the results of electrophysiological studies of the myoclonus. At age 5 years she experienced a stroke-like episode, and a diagnosis of MELAS was made at age 6 years on the basis of muscle biopsy findings. At age 9 years spontaneous and segmental myoclonus, predominantly affecting the upper extremities, developed because of complications. Electrophysiological examination, including of somatosensory-evoked potentials (SEPs) and averaged EMG for long loop reflexes, revealed so-called "giant SEP" and enhanced long loop reflexes reflecting cortical hyperexicitability. Jerk-locked averaging yielded no myoclonus related spikes, but myoclonus-contingent 4-5 Hz theta bursts appeared. These findings suggest that some types of MELAS may be associated with cortical types of myoclonus.
Brain Research, Nov 1, 2000
In human subjects, the excitability change of the brainstem was investigated over the course of t... more In human subjects, the excitability change of the brainstem was investigated over the course of the spindle oscillation. The investigation was carried out by a sequential analysis of brainstem auditory evoked potentials (BAEPs) with reference to one sequence of spindle oscillation. The method was based on the characteristics of BAEPs, i.e. far-field evoked potential. The brainstem revealed two types of excitability change: one in the lower ventral brainstem (wave-III components), and the other in the upper dorsal brainstem (wave-V components). The excitability in the dorsal brainstem showed an oscillation with one cycle period of about 1.5 s, whereas in the ventral brainstem, the excitability showed a long-range biphasic (decaying-growing) fluctuation. Both excitability changes in the brainstem preceded the spindle oscillation, and the phase was reversed during the emerging period of spindle oscillation. The results suggest a primary triggering mechanism of the brainstem for the spindle oscillation, which is independent of preceding cortical drives (K-complexes) upon the thalamus. The difference of the excitability change between the spindle oscillation and the paroxysmal discharge (spike-and-wave complex) was also discussed.
NeuroImage, Jan 15, 2008
Pain and somatosensory function (range 130 to 190 ms). In all subjects, the left and right fusifo... more Pain and somatosensory function (range 130 to 190 ms). In all subjects, the left and right fusiform response was earlier in time and stronger in dipole moment in response to face compared to food stimuli with main effects for latency (faces 155.5 ms (SE 5.8 ms); foods 177.3 ms (SE 4.1 ms); both p < 0.01) and amplitude (faces 46.1 nAm (SE 5.4 nAm); foods 26.0 nAm (SE 4.7 nAm); both p < 0.01). No significant condition X hemisphere interaction was found. Present findings are in-line with previous studies indicating areas within the fusiform gyrus most sensitive to face-specific stimuli. The findings also demonstrate the robustness of this phenomenon since a delayed and weaker fusiform response to non-socially relevant stimuli was observed in 100% of the subjects. The magnitude of the latency advantage for faces versus food (approximately 20 ms in healthy subjects), along with the robustness of the observation, offers potential utility as a biomarker for social impairment (where, by hypothesis, it is reduced) and thereby as an index for quantitative monitoring of socialization therapy.
日本てんかん学会プログラム・予稿集, Sep 11, 2002
Epilepsy & Behavior Reports, 2017
We administered perampanel (PER) to a bedridden 13-year-old male patient with dentatorubral-palli... more We administered perampanel (PER) to a bedridden 13-year-old male patient with dentatorubral-pallidoluysian atrophy (DRPLA). The DRPLA diagnosis was based on the presence of a CAG trinucleotide repeat in the ATN1 gene. The patient experienced continuous myoclonic seizures and weekly generalized tonic-clonic seizures (GTCs). PER stopped the patient's myoclonic seizures and reduced the GTCs to fragmented clonic seizures. The patient recovered his intellectual abilities and began to walk again with assistance. We suggest that PER be considered as one of the key drugs used to treat patients with DRPLA.
Psychiatry and Clinical Neurosciences, Sep 1, 1987
Psychiatry and Clinical Neurosciences, Apr 1, 1999
A vertex sharp wave followed by spindle (VS‐spindle) is one of the hallmarks of human stage 2 sle... more A vertex sharp wave followed by spindle (VS‐spindle) is one of the hallmarks of human stage 2 sleep. We recorded sleep electroencephalograms (EEG) simultaneously with brainstem auditory evoked potentials (BAEP) from nine healthy male subjects. To investigate the generating mechanism of the VS‐spindle, sequentially changing BAEP were analyzed around the VS‐spindle. The results revealed the preceding changes of wave‐V amplitude to the onset of the VS‐spindle. When the generator site of wave‐V in the brainstem was considered, the results suggest that the functional changes in the dorsal area of the midbrain–pontine junction participate in the organization of the VS‐spindle.
Brain & Development, Jul 1, 1995
The inter-and intrahemispheric phase characteristics were investigated on diffuse 3 Hz spike-and-... more The inter-and intrahemispheric phase characteristics were investigated on diffuse 3 Hz spike-and-wave complex (D3SW) in eight epileptic patients who were diagnosed with typical absence. The phase of D3SW was analyzed sequentially using cross-power spectral arrays dividing D3SW into two components (spike-and-wave complex, spike component). The phase of spike-and-wave complex preceded most at the midline structure, and delayed symmetrically toward the lateral side of each hemisphere in all cases, while not in all cases when spike component was investigated. In spite of this symmetry, there was sparse correlation in phase change between the homologous hemispheres. There was almost no linear correlation between the phase of spike-and-wave complex and the corresponding spike component. The author concludes that the 'centrencephalic system' hypothesis still plays an important role for the generation of D3SW, and suggest a mechanism other than the cortical recurrent inhibition for the generation of wave component.
Epilepsy Research, Aug 1, 2015
This study focused on the characteristic needle-like epileptic spikes of short duration and steep... more This study focused on the characteristic needle-like epileptic spikes of short duration and steep shape seen on magnetoencephalography (MEG) in patients diagnosed with focal cortical dysplasia (FCD) morphologically. We aimed to validate the analysis of MEG spike morphology as a noninvasive method of identifying the presence and location of FCD. MEG was collected by 204-channel helmet-shaped gradiometers. We analyzed MEG spike sources for 282 patients with symptomatic localization-related epilepsy. MEG showed clustered equivalent current dipoles when superimposed on their three-dimensional-magnetic resonance images (MRI) in 85 patients. Fifty-seven patients were excluded from our study, because they had destructive brain lesions or an insufficient number of spikes for statistical analysis. Twenty-eight patients (18 males, 10 females; aged 1-34 years) were finally matched to our inclusion criteria, and were categorized into three groups: FCD (7 patients), non-FCD (10 patients), and non-lesion (11 patients), based on the MRI findings. We measured the duration, amplitude, and tilt manually for at least 15 spikes per patient, and compared the three groups using a one-way analysis of variance, followed by the Tukey test when statistically significant (p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.05). In 17 patients with visible MRI lesions, we investigated the correlation between the depth of the lesion and the tilt using the Pearson product moment correlation. The average spike duration was significantly shorter in the FCD and non-lesion groups than in the non-FCD group (p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.05). The average amplitude was not significantly different between the three groups. The average spike tilt was significantly steeper in the FCD group than in the non-FCD group (p=0.0058). There was no significant difference between FCD and non-lesion patients in both duration and tilt. Our additional study revealed a significant negative correlation between the depth of the lesion and the average tilt (p=0.0009). MEG epileptiform discharges of short duration and steep tilt characterize FCD, especially when located at the superficial neocortical gyrus. We speculate that this particular spike morphology results from the intrinsic epileptogenicity of FCD. Morphological analysis of MEG spikes can evaluate the etiology of epileptogenic lesions and detect a strong, localized epileptogenic focus such as that typically observed in FCD.
Epilepsia, Dec 1, 1987
We compared the establishment of motor cortex kindling by daily electrical stimulation in adult c... more We compared the establishment of motor cortex kindling by daily electrical stimulation in adult cats and in 4-week-old kittens. All the adult cats and kittens examined reached a stable state of kindled seizures. There was no significant difference in afterdischarge (AD) thresholds, the course of clinical seizure development, or the number of stimuli required for the establishment of kindling between adult cats and kittens. During the development of the kindling stage, AD frequency increased in both adult cats and kittens, although AD duration did not show a clear change.
Brain & Development, 1985
Sixty patients (age-range one month to 14 years) with other types of epilepsy than infantile spas... more Sixty patients (age-range one month to 14 years) with other types of epilepsy than infantile spasms were treated with clonazepam. Disappearance of seizures and normalization of abnormal EEG with disappearance of seizures were recognized in 77% and 50%, respectively. Seizures disappeared in 71 % of the patients with generalized seizures and 89% of partial seizures. Improvement of abnormal EEG was noticed in 76% of diffuse paroxysms and in 67% of focal paroxysms. In excellent cases, mean effective dosages were 0.086 ± 0.021 mg/kg/day in infants and 0.057 ± 0.022 mg/kg/day in schoolchildren, this difference was statistically significant (p < O. 005). The incidence of side effects such as drowsiness and ataxia was only 5%.
PubMed, Mar 1, 1990
We designed a new cassette EEG recording system which consists of a recording block (an ambulator... more We designed a new cassette EEG recording system which consists of a recording block (an ambulatory-type data recorder and a newly developed pre-amplifier) and a reproduction block (a fixed-type data recorder, a personal computer equipped with A/D converting board and an intervening EEG device for a bandpass filter). This system was applied to 36 epileptic children, and 33 ictal records were obtained. The seizure type could be precisely classified by a comparative analysis of the data computed from this system and from the ictal symptoms. Three representative cases were presented with actual analysis procedures.
Brain Research, Aug 1, 1999
Ž. Ž. Simultaneous analysis of brainstem auditory evoked potentials BAEPs with reference to elect... more Ž. Ž. Simultaneous analysis of brainstem auditory evoked potentials BAEPs with reference to electroencephalography EEG was designed to examine the brainstem function corresponding to the EEG event. With this method, we investigated the brainstem function pre-and Ž. during the paroxysmal discharge in human absence seizures classified as primary generalized epilepsy PGE. Two types of functional Ž. change in the lower brainstem were revealed as parameters of wave-III components amplitude and area of BAEPs without significant Ž change in the upper brainstem. One was long-range biphasic fluctuation acceleration followed by abrupt deceleration with the maximum. y6.4 " 3.2 s before the seizure onset , and the other was rhythmic oscillation with 3 Hz. The latter, synchronized with the cortical spike-and-wave complex, imposed on the descending slope of the former. One important point is that both preceded the onset of cortical paroxysmal discharge. The results reappraise the classical hypothesis of ''centrencephalic system'' on seizure generating mechanism in human PGE. The results prove the primary triggering role of the lower brainstem that is independent of sleep-related synchronizations. The method is applicable to other types of EEG event for the investigation of brainstem involvement.
Neuroscience, Dec 1, 2002
öThe excitability change of the brainstem was investigated before and during the conspicuous epil... more öThe excitability change of the brainstem was investigated before and during the conspicuous epileptic discharge in six patients with generalized convulsive seizures. The discharge consisted of a short duration of recruiting rhythm, which was considered equivalent to the seizure discharge on electroencephalogram. The excitability of the brainstem was measured with the parameters (amplitude and area) of component waves (wave-III and-V) of brainstem auditory evoked potentials. The theoretical background of the analysis is that brainstem auditory evoked potentials are 'far-¢eld' potentials, by which they convey the information on the activity change of the brainstem even during the paroxysmal discharge within the cortex. The excitability of both the ventral (parameters of wave-III) and the dorsal brainstem (parameters of wave-V) exhibited a synchronized change (activation^inactivation). They were enhanced from 32.4 þ 0.4 s, reaching the maxima before the onset of the seizure discharge, and decayed corresponding to the emergence of the recruiting rhythm. The results suggest the possibility that the widespread (ventral and dorsal) and synchronized activation of the brainstem triggers the seizure discharge in human generalized epilepsy. During the widespread activation of the brainstem, both the thalamus and the cortex probably undergo a suppressed inhibitory state through the cholinergic activation, precipitating the seizure discharge.
Brain & Development, Feb 1, 2015
Purpose: We evaluated whether magnetoencephalography (MEG), in addition to surgery, was valuable ... more Purpose: We evaluated whether magnetoencephalography (MEG), in addition to surgery, was valuable for the diagnosis and management of epileptic syndromes in patients with neocortical epilepsy (NE). Methods: We studied MEG in 73 patients (29 females; aged 1-26 years; mean 10.3 years) for the clinical diagnosis of epilepsy and for preoperative evaluation. MEG data were recorded by 204-channel whole head gradiometers with a 600 Hz sampling rate. MEG spike sources were localized on magnetic resonance images (MRI) using a single dipole model to project equivalent current dipoles. Results: MEG localized an epileptic focus with single clustered dipoles in 24 (33%) of 73 NE patients: 16 (25%) of 64 symptomatic localization-related epilepsy (SLRE) patients and eight (89%) of nine idiopathic localization-related epilepsy (ILRE) patients. MEG provided advantageous information in 12 (50%) of 24 patients with clustered dipoles and confirmed the diagnosis in the remaining 12 (50%). Furthermore, the use of MEG resulted in changes to surgical treatments in nine (38%) patients and in medical management in eight (33%). MEG confirmed the diagnosis in eight (16%) of 49 patients with scattered dipoles. MRI identified a single lesion (28 patients, 38%), multiple lesions (5, 7%), and no lesion (40, 55%). MRI provided confirming information in 19 of 28 patients with a single lesion and 18 of them required surgical resections. MRI did not provide any supportive information in 54 (74%) patients with a single (9), multiple (5) and no lesion (40). Conclusion: Our study shows that MEG provides fundamental information to aid the choice of diagnostic and therapeutic procedures including changes in medication in addition to surgical treatments for NE.
International Congress Series, Jun 1, 2007
This study charted the magnetoencephalographic (MEG) findings with clinical course for atypical b... more This study charted the magnetoencephalographic (MEG) findings with clinical course for atypical benign partial epilepsy in childhood (ABPE). We discuss the etiology and epileptogenesis of this condition. Three patients with ABPE (age: 8-10 years old) underwent MEG analysis using a 204ch helmetshape MEG system. MEG showed unilateral epileptic activities over the frontal and temporal operculum and insular cortex during the worst seizures. The findings changed as the seizures were reduced by localized clustering of equivalent current dipoles (ECDs) at the unilateral temporal and frontal operculum near the primary motor area. We concluded that the localizations and directions of the ECDs in our patients during seizure remission resembled those of benign Rolandic epilepsy (BRE). We suggest a similar pathogenesis for ABPE and BRE.
The Journal of Pediatrics, Apr 1, 2008
Objective To evaluate the role of the gamma-aminobutyric acid type A (GABA A) receptor in Angelma... more Objective To evaluate the role of the gamma-aminobutyric acid type A (GABA A) receptor in Angelman syndrome (AS). Study design We performed [ 11 C]flumazenil positron emission tomography (PET) and examined GABA A receptor expression in 7 patients with AS of various genotypes (5 with the deletion, 1 with an imprinting defect [ID], and 1 with a UBE3A mutation) and 4 normal control healthy volunteers. Results Relative to the control subjects, the [ 11 C]flumazenil binding potentials (BPs) were significantly higher in the cerebral cortex and cerebellum in the 5 patients with the deletion and in the 1 patient with a UBE3A mutation, and were less frequently or barely increased in adult patients with the deletion and in the patient with IDs. Conclusions Total GABA A receptor expression was increased in patients with AS with various genotypes. We suggest that a developmental dysregulation of the GABA A receptor subunits occurs in patients with AS.
Clinical Neurophysiology, Oct 1, 2019
The results indicate that the absence of basic rhythm suggests delirium. The slowing of basic rhy... more The results indicate that the absence of basic rhythm suggests delirium. The slowing of basic rhythm and the absence of basic rhythm attenuation during the eyes-open state were found in the patients with dementia and psychosis, respectively. Normal EEG pattern was observed in depressed patients. The total ICDSC scores in these confused patients were high regardless of the differences in EEG patterns. It would be beneficial to use EEG power spectrum to understand the pathophysiology of confused patients to enable the appropriate treatment.
Clinical Neurophysiology, Oct 1, 2010
Neuroscience, 2012
A K-complex (KC) in the electroencephalographs (EEGs) indicates a moderate depth of slow-wave sle... more A K-complex (KC) in the electroencephalographs (EEGs) indicates a moderate depth of slow-wave sleep (SWS) in humans and animals. The cortical activities are upregulated during the periods between the KCs (&amp;quot;up state&amp;quot;), and it is proposed that temporarily stored memories during wakeful periods will be consolidated during these periods. Although the underlying mechanism for KCs is proposed to be in the cortex itself, the involvement of the brainstem has not been explored. Here we investigate the excitability changes of the brainstem preceding, during, and after KCs in humans. We simultaneously recorded brainstem auditory evoked potentials (BAEPs) with EEGs, and sequentially analyzed BAEPs around the KCs. The results showed a transient activation of the ventral brainstem preceding the KC and a sustained activation of the dorsal brainstem outlasting the KC. Thus, it is suggested that KCs are triggered by the activation of the brainstem and that the &amp;quot;up state&amp;quot; is maintained by the sustained activation of the brainstem.
Brain & Development, Jul 1, 1992
A 9-year-old female MELAS patient with myoclonus is reported, with emphasis on the results of ele... more A 9-year-old female MELAS patient with myoclonus is reported, with emphasis on the results of electrophysiological studies of the myoclonus. At age 5 years she experienced a stroke-like episode, and a diagnosis of MELAS was made at age 6 years on the basis of muscle biopsy findings. At age 9 years spontaneous and segmental myoclonus, predominantly affecting the upper extremities, developed because of complications. Electrophysiological examination, including of somatosensory-evoked potentials (SEPs) and averaged EMG for long loop reflexes, revealed so-called "giant SEP" and enhanced long loop reflexes reflecting cortical hyperexicitability. Jerk-locked averaging yielded no myoclonus related spikes, but myoclonus-contingent 4-5 Hz theta bursts appeared. These findings suggest that some types of MELAS may be associated with cortical types of myoclonus.
Brain Research, Nov 1, 2000
In human subjects, the excitability change of the brainstem was investigated over the course of t... more In human subjects, the excitability change of the brainstem was investigated over the course of the spindle oscillation. The investigation was carried out by a sequential analysis of brainstem auditory evoked potentials (BAEPs) with reference to one sequence of spindle oscillation. The method was based on the characteristics of BAEPs, i.e. far-field evoked potential. The brainstem revealed two types of excitability change: one in the lower ventral brainstem (wave-III components), and the other in the upper dorsal brainstem (wave-V components). The excitability in the dorsal brainstem showed an oscillation with one cycle period of about 1.5 s, whereas in the ventral brainstem, the excitability showed a long-range biphasic (decaying-growing) fluctuation. Both excitability changes in the brainstem preceded the spindle oscillation, and the phase was reversed during the emerging period of spindle oscillation. The results suggest a primary triggering mechanism of the brainstem for the spindle oscillation, which is independent of preceding cortical drives (K-complexes) upon the thalamus. The difference of the excitability change between the spindle oscillation and the paroxysmal discharge (spike-and-wave complex) was also discussed.
NeuroImage, Jan 15, 2008
Pain and somatosensory function (range 130 to 190 ms). In all subjects, the left and right fusifo... more Pain and somatosensory function (range 130 to 190 ms). In all subjects, the left and right fusiform response was earlier in time and stronger in dipole moment in response to face compared to food stimuli with main effects for latency (faces 155.5 ms (SE 5.8 ms); foods 177.3 ms (SE 4.1 ms); both p < 0.01) and amplitude (faces 46.1 nAm (SE 5.4 nAm); foods 26.0 nAm (SE 4.7 nAm); both p < 0.01). No significant condition X hemisphere interaction was found. Present findings are in-line with previous studies indicating areas within the fusiform gyrus most sensitive to face-specific stimuli. The findings also demonstrate the robustness of this phenomenon since a delayed and weaker fusiform response to non-socially relevant stimuli was observed in 100% of the subjects. The magnitude of the latency advantage for faces versus food (approximately 20 ms in healthy subjects), along with the robustness of the observation, offers potential utility as a biomarker for social impairment (where, by hypothesis, it is reduced) and thereby as an index for quantitative monitoring of socialization therapy.
日本てんかん学会プログラム・予稿集, Sep 11, 2002
Epilepsy & Behavior Reports, 2017
We administered perampanel (PER) to a bedridden 13-year-old male patient with dentatorubral-palli... more We administered perampanel (PER) to a bedridden 13-year-old male patient with dentatorubral-pallidoluysian atrophy (DRPLA). The DRPLA diagnosis was based on the presence of a CAG trinucleotide repeat in the ATN1 gene. The patient experienced continuous myoclonic seizures and weekly generalized tonic-clonic seizures (GTCs). PER stopped the patient's myoclonic seizures and reduced the GTCs to fragmented clonic seizures. The patient recovered his intellectual abilities and began to walk again with assistance. We suggest that PER be considered as one of the key drugs used to treat patients with DRPLA.
Psychiatry and Clinical Neurosciences, Sep 1, 1987
Psychiatry and Clinical Neurosciences, Apr 1, 1999
A vertex sharp wave followed by spindle (VS‐spindle) is one of the hallmarks of human stage 2 sle... more A vertex sharp wave followed by spindle (VS‐spindle) is one of the hallmarks of human stage 2 sleep. We recorded sleep electroencephalograms (EEG) simultaneously with brainstem auditory evoked potentials (BAEP) from nine healthy male subjects. To investigate the generating mechanism of the VS‐spindle, sequentially changing BAEP were analyzed around the VS‐spindle. The results revealed the preceding changes of wave‐V amplitude to the onset of the VS‐spindle. When the generator site of wave‐V in the brainstem was considered, the results suggest that the functional changes in the dorsal area of the midbrain–pontine junction participate in the organization of the VS‐spindle.
Brain & Development, Jul 1, 1995
The inter-and intrahemispheric phase characteristics were investigated on diffuse 3 Hz spike-and-... more The inter-and intrahemispheric phase characteristics were investigated on diffuse 3 Hz spike-and-wave complex (D3SW) in eight epileptic patients who were diagnosed with typical absence. The phase of D3SW was analyzed sequentially using cross-power spectral arrays dividing D3SW into two components (spike-and-wave complex, spike component). The phase of spike-and-wave complex preceded most at the midline structure, and delayed symmetrically toward the lateral side of each hemisphere in all cases, while not in all cases when spike component was investigated. In spite of this symmetry, there was sparse correlation in phase change between the homologous hemispheres. There was almost no linear correlation between the phase of spike-and-wave complex and the corresponding spike component. The author concludes that the 'centrencephalic system' hypothesis still plays an important role for the generation of D3SW, and suggest a mechanism other than the cortical recurrent inhibition for the generation of wave component.
Epilepsy Research, Aug 1, 2015
This study focused on the characteristic needle-like epileptic spikes of short duration and steep... more This study focused on the characteristic needle-like epileptic spikes of short duration and steep shape seen on magnetoencephalography (MEG) in patients diagnosed with focal cortical dysplasia (FCD) morphologically. We aimed to validate the analysis of MEG spike morphology as a noninvasive method of identifying the presence and location of FCD. MEG was collected by 204-channel helmet-shaped gradiometers. We analyzed MEG spike sources for 282 patients with symptomatic localization-related epilepsy. MEG showed clustered equivalent current dipoles when superimposed on their three-dimensional-magnetic resonance images (MRI) in 85 patients. Fifty-seven patients were excluded from our study, because they had destructive brain lesions or an insufficient number of spikes for statistical analysis. Twenty-eight patients (18 males, 10 females; aged 1-34 years) were finally matched to our inclusion criteria, and were categorized into three groups: FCD (7 patients), non-FCD (10 patients), and non-lesion (11 patients), based on the MRI findings. We measured the duration, amplitude, and tilt manually for at least 15 spikes per patient, and compared the three groups using a one-way analysis of variance, followed by the Tukey test when statistically significant (p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.05). In 17 patients with visible MRI lesions, we investigated the correlation between the depth of the lesion and the tilt using the Pearson product moment correlation. The average spike duration was significantly shorter in the FCD and non-lesion groups than in the non-FCD group (p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.05). The average amplitude was not significantly different between the three groups. The average spike tilt was significantly steeper in the FCD group than in the non-FCD group (p=0.0058). There was no significant difference between FCD and non-lesion patients in both duration and tilt. Our additional study revealed a significant negative correlation between the depth of the lesion and the average tilt (p=0.0009). MEG epileptiform discharges of short duration and steep tilt characterize FCD, especially when located at the superficial neocortical gyrus. We speculate that this particular spike morphology results from the intrinsic epileptogenicity of FCD. Morphological analysis of MEG spikes can evaluate the etiology of epileptogenic lesions and detect a strong, localized epileptogenic focus such as that typically observed in FCD.
Epilepsia, Dec 1, 1987
We compared the establishment of motor cortex kindling by daily electrical stimulation in adult c... more We compared the establishment of motor cortex kindling by daily electrical stimulation in adult cats and in 4-week-old kittens. All the adult cats and kittens examined reached a stable state of kindled seizures. There was no significant difference in afterdischarge (AD) thresholds, the course of clinical seizure development, or the number of stimuli required for the establishment of kindling between adult cats and kittens. During the development of the kindling stage, AD frequency increased in both adult cats and kittens, although AD duration did not show a clear change.
Brain & Development, 1985
Sixty patients (age-range one month to 14 years) with other types of epilepsy than infantile spas... more Sixty patients (age-range one month to 14 years) with other types of epilepsy than infantile spasms were treated with clonazepam. Disappearance of seizures and normalization of abnormal EEG with disappearance of seizures were recognized in 77% and 50%, respectively. Seizures disappeared in 71 % of the patients with generalized seizures and 89% of partial seizures. Improvement of abnormal EEG was noticed in 76% of diffuse paroxysms and in 67% of focal paroxysms. In excellent cases, mean effective dosages were 0.086 ± 0.021 mg/kg/day in infants and 0.057 ± 0.022 mg/kg/day in schoolchildren, this difference was statistically significant (p < O. 005). The incidence of side effects such as drowsiness and ataxia was only 5%.