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1.
Sci Total Environ ; 816: 151573, 2022 Apr 10.
Article in English | MEDLINE | ID: mdl-34774626

ABSTRACT

Accidental leakage of radionuclides from the Fukushima Nuclear Power Plant (FNPP1) took place in the aftermath of the catastrophic tsunamis associated with the Great East Japan Earthquake that occurred on March 11, 2011. Significant amount of radionuclides released into the atmosphere were reportedly transported and deposited on land located near FNPP1. The Niida River, Fukushima, Japan, has been recognized as a terrestrial source of highly contaminated suspended radiocesium adhering to sediment particles in the ocean through the river mouth as a result of hydrological processes. Remaining scientific questions include the oceanic dispersal and inventories of the sediments and suspended radiocesium in the ocean floor derived from the Niida River. Complementing limited in situ data, we developed a quadruple nested 3D ocean circulation and sediment transport model in an extremely high-resolution configuration to quantify the transport processes of the suspended radiocesium. Particularly, we investigated the storm and subsequent floods associated with Typhoon 201326 (Wipha) that passed off the Fukushima coast in October 2013, and subsequently promoted precipitation to a considerable extent and associated riverine freshwater discharge along with sediment outfluxes to the ocean. Using in situ bed sediment core data obtained from regions near the river mouth, we conducted a quantitative assessment of the accumulation and erosion of the sediments and explored the resultant suspended radiocesium distribution around the river mouth and nearshore areas along the Fukushima coast. We identified three major accumulative areas, near the river mouth within an area < 1 km, around the breakwaters in the north of the river mouth, and along the southern coastal area, while offshore and northward transports were minor. The present study clearly exhibits substantial retention of the land-derived radiocesium adsorbed to the sediments in the coastal areas, leading to possible long-term influences on the surrounding marine environment.


Subject(s)
Fukushima Nuclear Accident , Radiation Monitoring , Water Pollutants, Radioactive , Cesium Radioisotopes/analysis , Floods , Japan , Rivers , Water Pollutants, Radioactive/analysis
2.
Environ Sci Technol ; 54(21): 13778-13785, 2020 11 03.
Article in English | MEDLINE | ID: mdl-33073983

ABSTRACT

Concentrations of 137Cs in seawater, seabed sediment, and pore water collected from the area around Fukushima were investigated from 2015 to 2018, and the potential of coastal sediments to supply radiocesium to the bottom environment was evaluated. The 137Cs concentration in the pore water ranged from 33 to 1934 mBq L-1 and was 10-40 times higher than that in the overlying water (seawater overlying within 30 cm on the seabed). At most stations, the 137Cs concentrations in the overlying water and the pore water were approximately proportional to those in the sediment. The conditional partition coefficient between pore water and sediment was [0.9-14] × 102 L kg-1, independent of the year of sampling. These results indicated that an equilibrium of 137Cs between pore water and sediment has been established in a relatively short period, and 137Cs in the pore water is gradually exported to seawater near the seabed. A simple box model estimation based on these results showed that 137Cs in the sediment decreased by about 6% per year by desorption/diffusion of 137Cs from the seabed.


Subject(s)
Fukushima Nuclear Accident , Radiation Monitoring , Water Pollutants, Radioactive , Cesium Radioisotopes/analysis , Japan , Seawater , Water , Water Pollutants, Radioactive/analysis
3.
Chemosphere ; 252: 126524, 2020 Aug.
Article in English | MEDLINE | ID: mdl-32217409

ABSTRACT

129I released from the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident has been observed in the atmospheric, terrestrial and oceanic environments, and it also entered the marine sediments via dispersion by sea water movement and deposition around Japan. However, there have been few studies of marine sediment cores in contrast to the large number of studies on seawater. In this work, a sediment core collected near FDNPP was analyzed for 129I. It is observed that the 129I/127I atomic ratios in this sediment core are comparable to those in the seawater and sediments collected from offshore Fukushima after the accident, but 2 orders of magnitude higher than those in seawater in this region before the accident, suggesting the significant amount of 129I has been transferred and incorporated to the offshore shallow sediments. The difference in environmental behavior between 129I and 137Cs is discussed based on their depth distributions in the sediment core in comparison with the grain size distribution of sediments. The peak concentrations of iodine isotopes were found in a relatively deeper layer than radiocesium. Radiocesium follows the distribution of fine grains in the sediment core, implying its high association to fine grains.


Subject(s)
Fukushima Nuclear Accident , Iodine Radioisotopes/analysis , Radiation Monitoring , Water Pollutants, Radioactive/analysis , Cesium Radioisotopes , Geologic Sediments , Japan , Nuclear Power Plants , Oceans and Seas , Seawater , Water Movements
4.
Sci Rep ; 9(1): 11807, 2019 08 14.
Article in English | MEDLINE | ID: mdl-31413276

ABSTRACT

Radioactive particles were released into the environment during the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident. Many studies have been conducted to elucidate the chemical composition of released radioactive particles in order to understand their formation process. However, whether radioactive particles contain nuclear fuel radionuclides remains to be investigated. Here, we report the first determination of Pu isotopes in radioactive particles. To determine the Pu isotopes (239Pu, 240Pu and 241Pu) in radioactive particles derived from the FDNPP accident which were free from the influence of global fallout, radiochemical analysis and inductively coupled plasma-mass spectrometry measurements were conducted. Radioactive particles derived from unit 1 and unit 2 or 3 were analyzed. For the radioactive particles derived from unit 1, activities of 239+240Pu and 241Pu were (1.70-7.06) × 10-5 Bq and (4.10-8.10) × 10-3 Bq, respectively and atom ratios of 240Pu/239Pu and 241Pu/239Pu were 0.330-0.415 and 0.162-0.178, respectively. These ratios were consistent with the simulation results from ORIGEN code and measurements from various environmental samples. In contrast, Pu was not detected in the radioactive particles derived from unit 2 or 3. The difference in Pu contents is clear evidence towards different formation processes of radioactive particles, and detailed formation processes can be investigated from Pu analysis.

6.
Genet Med ; 21(6): 1295-1307, 2019 06.
Article in English | MEDLINE | ID: mdl-30349098

ABSTRACT

PURPOSE: Pathogenic variants in ARID1B are one of the most frequent causes of intellectual disability (ID) as determined by large-scale exome sequencing studies. Most studies published thus far describe clinically diagnosed Coffin-Siris patients (ARID1B-CSS) and it is unclear whether these data are representative for patients identified through sequencing of unbiased ID cohorts (ARID1B-ID). We therefore sought to determine genotypic and phenotypic differences between ARID1B-ID and ARID1B-CSS. In parallel, we investigated the effect of different methods of phenotype reporting. METHODS: Clinicians entered clinical data in an extensive web-based survey. RESULTS: 79 ARID1B-CSS and 64 ARID1B-ID patients were included. CSS-associated dysmorphic features, such as thick eyebrows, long eyelashes, thick alae nasi, long and/or broad philtrum, small nails and small or absent fifth distal phalanx and hypertrichosis, were observed significantly more often (p < 0.001) in ARID1B-CSS patients. No other significant differences were identified. CONCLUSION: There are only minor differences between ARID1B-ID and ARID1B-CSS patients. ARID1B-related disorders seem to consist of a spectrum, and patients should be managed similarly. We demonstrated that data collection methods without an explicit option to report the absence of a feature (such as most Human Phenotype Ontology-based methods) tended to underestimate gene-related features.


Subject(s)
DNA-Binding Proteins/genetics , DNA-Binding Proteins/metabolism , Transcription Factors/genetics , Transcription Factors/metabolism , Abnormalities, Multiple/genetics , Adolescent , Adult , Child , Child, Preschool , Chromosomal Proteins, Non-Histone/genetics , Exome , Face/abnormalities , Female , Genetic Association Studies/methods , Genetic Variation/genetics , Hand Deformities, Congenital/genetics , Humans , Infant , Infant, Newborn , Intellectual Disability/genetics , Male , Micrognathism/genetics , Middle Aged , Mutation , Neck/abnormalities , Penetrance
7.
J Environ Radioact ; 172: 163-172, 2017 Jun.
Article in English | MEDLINE | ID: mdl-28380392

ABSTRACT

We investigated temporal changes of the contamination of oceanic zooplankton with radiocesium (134Cs and 137Cs) derived from the Fukushima Dai-ichi Nuclear Power Plant accident one month to three years after the accident at subarctic and subtropical stations (1900 and 900-1000 km from the plant, respectively) in the western North Pacific. The maximum activity concentrations of 137Cs in zooplankton were two orders of magnitude higher than the pre-accident level. In the first four months after the accident, the activity concentrations of radiocesium in subtropical zooplankton decreased rapidly, but no similar change was observed at the subarctic station. The radiocesium derived from atmospheric deposition rapidly decreased as a result of seawater mixing. Thus, most of the subtropical zooplankton (with short lifespans) that had taken up radiocesium just after the accident were probably replaced by newly hatched zooplankton within four months of the accident, whereas subarctic zooplankton (with long lifespans) that were highly contaminated with radiocesium were still alive four months after the accident. By the end of the study, 137Cs activity concentrations in subtropical zooplankton were still high, whereas the activity concentrations in subarctic zooplankton had decreased to nearly the pre-accident level. The former concentrations were probably influenced by a secondary supply of radiocesium via advection of subtropical mode water that was highly contaminated with Fukushima-derived radiocesium. Unexpectedly, at the subarctic station, the radiocesium activity concentrations in surface zooplankton were lower than those in subsurface zooplankton, whereas the opposite relationship was observed in surface and subsurface seawater. Because carnivores predominated in the subsurface zooplankton community, we hypothesize that the higher radiocesium activity concentrations in subsurface zooplankton were influenced by bioaccumulation. We conclude that radiocesium activity concentrations in zooplankton are influenced not only by the supply of radiocesium to the environment but also by the characteristics of the zooplankton community.


Subject(s)
Cesium Radioisotopes/analysis , Fukushima Nuclear Accident , Radiation Monitoring , Water Pollutants, Radioactive/analysis , Zooplankton/chemistry , Animals , Japan , Seawater/chemistry
8.
PLoS One ; 12(2): e0173073, 2017.
Article in English | MEDLINE | ID: mdl-28245277

ABSTRACT

Recent development of environmental DNA (eDNA) analysis allows us to survey underwater macro-organisms easily and cost effectively; however, there have been no reports on eDNA detection or quantification for jellyfish. Here we present the first report on an eDNA analysis of marine jellyfish using Japanese sea nettle (Chrysaora pacifica) as a model species by combining a tank experiment with spatial and temporal distribution surveys. We performed a tank experiment monitoring eDNA concentrations over a range of time intervals after the introduction of jellyfish, and quantified the eDNA concentrations by quantitative real-time PCR. The eDNA concentrations peaked twice, at 1 and 8 h after the beginning of the experiment, and became stable within 48 h. The estimated release rates of the eDNA in jellyfish were higher than the rates previously reported in fishes. A spatial survey was conducted in June 2014 in Maizuru Bay, Kyoto, in which eDNA was collected from surface water and sea floor water samples at 47 sites while jellyfish near surface water were counted on board by eye. The distribution of eDNA in the bay corresponded with the distribution of jellyfish inferred by visual observation, and the eDNA concentration in the bay was ~13 times higher on the sea floor than on the surface. The temporal survey was conducted from March to November 2014, in which jellyfish were counted by eye every morning while eDNA was collected from surface and sea floor water at three sampling points along a pier once a month. The temporal fluctuation pattern of the eDNA concentrations and the numbers of observed individuals were well correlated. We conclude that an eDNA approach is applicable for jellyfish species in the ocean.


Subject(s)
DNA/analysis , Fishes/genetics , Animals , Ecosystem , Environmental Monitoring , Fishes/physiology , Models, Theoretical , Real-Time Polymerase Chain Reaction
10.
PLoS One ; 11(3): e0149786, 2016.
Article in English | MEDLINE | ID: mdl-26933889

ABSTRACT

Recent studies in streams and ponds have demonstrated that the distribution and biomass of aquatic organisms can be estimated by detection and quantification of environmental DNA (eDNA). In more open systems such as seas, it is not evident whether eDNA can represent the distribution and biomass of aquatic organisms because various environmental factors (e.g., water flow) are expected to affect eDNA distribution and concentration. To test the relationships between the distribution of fish and eDNA, we conducted a grid survey in Maizuru Bay, Sea of Japan, and sampled surface and bottom waters while monitoring biomass of the Japanese jack mackerel (Trachurus japonicus) using echo sounder technology. A linear model showed a high R(2) value (0.665) without outlier data points, and the association between estimated eDNA concentrations from the surface water samples and echo intensity was significantly positive, suggesting that the estimated spatial variation in eDNA concentration can reflect the local biomass of the jack mackerel. We also found that a best-fit model included echo intensity obtained within 10-150 m from water sampling sites, indicating that the estimated eDNA concentration most likely reflects fish biomass within 150 m in the bay. Although eDNA from a wholesale fish market partially affected eDNA concentration, we conclude that eDNA generally provides a 'snapshot' of fish distribution and biomass in a large area. Further studies in which dynamics of eDNA under field conditions (e.g., patterns of release, degradation, and diffusion of eDNA) are taken into account will provide a better estimate of fish distribution and biomass based on eDNA.


Subject(s)
DNA/genetics , Perciformes/genetics , Animals , Bays , Biomass , Ecosystem , Japan
11.
J Diabetes Sci Technol ; 9(2): 200-5, 2015 Mar.
Article in English | MEDLINE | ID: mdl-25633966

ABSTRACT

ARKRAY, Inc developed the world's first automatic glycohemoglobin analyzer based on HPLC (1981). After that, ARKRAY developed enzymatic HbA1c assay "CinQ HbA1c" with the spread and diversification of HbA1c measurement (2007). CinQ HbA1c is the kit of Clinical Chemistry Analyzer, which uses fructosyl peptide oxidase (FPOX) for a measurement reaction. This report mainly indicates the developmental background, measurement principle, and future of the enzymatic method HbA1c reagent.


Subject(s)
Amino Acid Oxidoreductases/blood , Blood Chemical Analysis/methods , Diabetes Mellitus/blood , Glycated Hemoglobin/analysis , Reagent Kits, Diagnostic , Blood Chemical Analysis/history , Enzyme Assays/history , History, 20th Century , Humans , Reagent Kits, Diagnostic/history
12.
Environ Sci Technol ; 48(16): 9070-8, 2014 Aug 19.
Article in English | MEDLINE | ID: mdl-25050458

ABSTRACT

Atmospheric deposition of Pu isotopes from the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident has been observed in the terrestrial environment around the FDNPP site; however, their deposition in the marine environment has not been studied. The possible contamination of Pu in the marine environment has attracted great scientific and public concern. To fully understand this possible contamination of Pu isotopes from the FDNPP accident to the marine environment, we collected marine sediment core samples within the 30 km zone around the FDNPP site in the western North Pacific about two years after the accident. Pu isotopes ((239)Pu, (240)Pu, and (241)Pu) and radiocesium isotopes ((134)Cs and (137)Cs) in the samples were determined. The high activities of radiocesium and the (134)Cs/(137)Cs activity ratios with values around 1 (decay corrected to 15 March 2011) suggested that these samples were contaminated by the FDNPP accident-released radionuclides. However, the activities of (239+240)Pu and (241)Pu were low compared with the background level before the FDNPP accident. The Pu atom ratios ((240)Pu/(239)Pu and (241)Pu/(239)Pu) suggested that global fallout and the pacific proving ground (PPG) close-in fallout are the main sources for Pu contamination in the marine sediments. As Pu isotopes are particle-reactive and they can be easily incorporated with the marine sediments, we concluded that the release of Pu isotopes from the FDNPP accident to the marine environment was negligible.


Subject(s)
Fukushima Nuclear Accident , Geologic Sediments/analysis , Plutonium/analysis , Water Pollutants, Radioactive/analysis , Cesium Radioisotopes/analysis , Radiation Monitoring , Seawater
13.
Pediatr Transplant ; 18(2): E52-6, 2014 Mar.
Article in English | MEDLINE | ID: mdl-24373121

ABSTRACT

A 15-yr-old boy presented with an anterior mediastinal mass, multiple lung metastases and obstruction of the left brachiocephalic vein, the superior vena cava and the subclavian vein. Tumor biopsy by CT guidance confirmed a diagnosis of GCT. Five courses of BEP therapy were performed, and CT of the chest revealed reduction in the anterior mediastinal mass and disappearance of the multiple lung metastases. We performed the anterior mediastinal mass extraction followed by adjuvant chemotherapy consisting of ICE and TIP. However, the AFP levels became elevated soon after. Abnormal accumulation was observed in the right upper lung by DW-MRI. After the operation, two courses of TI chemotherapy and two courses of HDCT followed by auto-PBSCT were performed. He was complicated with auditory disorder and renal dysfunction. Although HDCT followed by auto-PBSCT was effective for the relapsed primary mediastinal GCT, a treatment strategy avoiding late complications is warranted.


Subject(s)
Antineoplastic Agents/therapeutic use , Lung Neoplasms/therapy , Neoplasms, Germ Cell and Embryonal/therapy , Peripheral Blood Stem Cell Transplantation/methods , Adolescent , Antineoplastic Agents/chemistry , Biopsy , Brachiocephalic Veins/pathology , Diffusion Magnetic Resonance Imaging , Fluorodeoxyglucose F18/chemistry , Humans , Lung Neoplasms/immunology , Magnetic Resonance Imaging , Male , Neoplasm Metastasis , Neoplasms, Germ Cell and Embryonal/immunology , Positron-Emission Tomography , Prognosis , Recurrence , Subclavian Vein/pathology , Tomography, X-Ray Computed , Treatment Outcome , Vena Cava, Superior/pathology
14.
Biochimie ; 93(5): 817-22, 2011 May.
Article in English | MEDLINE | ID: mdl-21288476

ABSTRACT

RNA-binding proteins (RBPs) play a vital role in the post-transcriptional regulation of gene expression during neuronal differentiation and synaptic plasticity. One such RBP family, the neuronal Hu protein family, serves as an early marker of neuronal differentiation and targets several mRNAs containing adenine/uridine-rich elements. Recently, we reported that one of the neuronal Hu proteins, HuD stimulates cap-dependent translation through interactions with eIF4A and poly (A) tail. Nevertheless, little is known with respect to how neuronal Hu proteins contribute to the local translation of target mRNAs in neuronal differentiation. Here, we found that neuronal Hu proteins, but not the ubiquitously expressed HuR protein, directly interact with the light chain of microtubule-associated proteins MAP1B (LC1). We also show that HuD simultaneously binds both RNA and LC1 in vitro and that it tightly associates with microtubules in cells in an LC1-dependent manner, raising the possibility that HuD recruits target mRNAs to microtubules. These results uncover the neuronal binding partners for neuron-specific Hu proteins and suggest the involvement of Hu proteins in microtubule-mediated regulation of mRNA expression within neuronal processes.


Subject(s)
ELAV Proteins/metabolism , Microtubule-Associated Proteins/metabolism , Microtubules/metabolism , Neurons/metabolism , RNA-Binding Proteins/metabolism , RNA/metabolism , Animals , ELAV-Like Protein 4 , HeLa Cells , Humans , Mice , PC12 Cells , Protein Binding , Protein Interaction Domains and Motifs , Protein Structure, Tertiary , Rats , Two-Hybrid System Techniques
15.
Brain Dev ; 33(3): 213-20, 2011 Mar.
Article in English | MEDLINE | ID: mdl-21067877

ABSTRACT

As seizures in the neonatal period have generally been identified only by direct clinical observation, there is frequently a lack of objectivity as to whether seizures are categorized as epilepsies or non-epilepsies. A major characteristic of neonatal seizures is electro-clinical dissociation and some electro-graphic seizures do not produce clinical symptoms. It is difficult to correctly identify real epilepsies or epileptic syndromes in the neonatal period without ictal electroencephalogram (EEG). Some epileptic syndromes starting in the neonatal period such as early myoclonic encephalopathy, Ohtahara syndrome, or migrating partial seizures in infancy are categorized as malignant epilepsies. A suppression-burst EEG pattern (SBP) is usually seen in neonates with serious brain damage, malignant epileptic syndromes or other neurological conditions. However SBP has not been consistently defined in the literature. We review malignant epilepsies and benign familial and non-familial neonatal seizures starting in the neonatal period and propose the characteristics of SBP in Ohtahara syndrome. Epileptic encephalopathies with SBP in the neonatal period are known to evolve into relatively few types of epileptic syndromes. We emphasize the importance of ictal EEG for diagnosis and treatment of malignant epilepsies and epileptic syndromes in the neonatal period.


Subject(s)
Epilepsy/therapy , Brain Damage, Chronic/etiology , Chronic Disease , Electroencephalography , Epilepsies, Myoclonic/complications , Epilepsy/classification , Epilepsy/diagnosis , Epilepsy, Benign Neonatal/pathology , Epilepsy, Benign Neonatal/therapy , Humans , Infant, Newborn , Male
16.
Hum Brain Mapp ; 31(11): 1627-42, 2010 Nov.
Article in English | MEDLINE | ID: mdl-20143383

ABSTRACT

Human activities often involve hand-motor responses following external auditory-verbal commands. It has been believed that hand movements are predominantly driven by the contralateral primary sensorimotor cortex, whereas auditory-verbal information is processed in both superior temporal gyri. It remains unknown whether cortical activation in the superior temporal gyrus during an auditory-motor task is affected by laterality of hand-motor responses. Here, event-related γ-oscillations were intracranially recorded as quantitative measures of cortical activation; we determined how cortical structures were activated by auditory-cued movement using each hand in 15 patients with focal epilepsy. Auditory-verbal stimuli elicited augmentation of γ-oscillations in a posterior portion of the superior temporal gyrus, whereas hand-motor responses elicited γ-augmentation in the pre- and postcentral gyri. The magnitudes of such γ-augmentation in the superior temporal, precentral, and postcentral gyri were significantly larger when the hand contralateral to the recorded hemisphere was required to be used for motor responses, compared with when the ipsilateral hand was. The superior temporal gyrus in each hemisphere might play a greater pivotal role when the contralateral hand needs to be used for motor responses, compared with when the ipsilateral hand does.


Subject(s)
Brain Waves/physiology , Cerebral Cortex/physiopathology , Epilepsies, Partial/physiopathology , Evoked Potentials/physiology , Acoustic Stimulation , Adolescent , Brain Mapping , Child , Cues , Electrodes, Implanted , Electroencephalography , Female , Functional Laterality/physiology , Humans , Image Processing, Computer-Assisted , Male , Motor Activity/physiology , Movement/physiology
17.
Clin Neurophysiol ; 121(3): 366-75, 2010 Mar.
Article in English | MEDLINE | ID: mdl-20075003

ABSTRACT

OBJECTIVE: Several human studies have demonstrated that the amplitudes of cortical oscillations are altered by various sensorimotor and cognitive tasks. Event-related augmentation of gamma oscillations and attenuation of alpha and beta oscillations have been often used as surrogate markers of cortical activation elicited by tasks especially in presurgical identification of eloquent cortices. In the present study, we addressed a question whether somatosensory-related gamma augmentation 'precedes' or 'co-occurs with' somatosensory-related attenuation of alpha-beta oscillations. METHODS: We studied 10 patients who underwent intracranial electrocorticography for epilepsy surgery, and determined the temporal and spatial characteristics of median-nerve somatosensory-related amplitude changes at gamma- (30-100Hz), beta- (14-28Hz) and alpha-band (8-12Hz) oscillations. RESULTS: We found that somatosensory-related gamma augmentation involving the post- and pre-central gyri evolved into beta and alpha augmentation, which was subsequently followed by beta and alpha attenuation involving the post- and pre-central gyri. CONCLUSIONS: These observations support the hypothesis that somatosensory-related gamma augmentation but not alpha-beta attenuation represents the initial cortical processing for external somatosensory stimuli. Somatosensory-related alpha-beta attenuation appears to represent a temporally distinct stage of somatosensory processing. SIGNIFICANCE: The present study has increased our understanding of event-related gamma augmentation and alpha-beta attenuation seen on electrocorticography.


Subject(s)
Alpha Rhythm , Beta Rhythm , Evoked Potentials, Somatosensory/physiology , Somatosensory Cortex/physiology , Action Potentials/physiology , Adolescent , Algorithms , Biological Clocks/physiology , Child , Child, Preschool , Electric Stimulation , Female , Humans , Male , Median Nerve/physiology , Motor Cortex/physiology , Nerve Net/physiology , Neural Conduction/physiology , Reaction Time/physiology , Sensory Thresholds/physiology , Signal Processing, Computer-Assisted , Time Factors , Touch Perception/physiology
18.
Neuroimage ; 49(3): 2735-45, 2010 Feb 01.
Article in English | MEDLINE | ID: mdl-19874898

ABSTRACT

Both superior temporal gyrus and inferior Rolandic area have been reported to be involved in perception and production of speech in humans. Here, we determined how these cortical structures were activated by listening and subsequent overt articulation of syllables, by measuring event-related gamma-oscillations as quantitative measures of cortical activation. Fifteen subjects were presented an auditory syllable consisting of either "fee [fi:]," "faa [falpha:]," "hee [hi:]," or "haa [halpha:]," and were instructed to overtly repeat each given syllable. Gamma-oscillations in the superior temporal gyrus were highly augmented during syllable-presentation, least augmented at the onset of syllable-articulation, and again highly augmented following syllable-articulation. Gamma-oscillations were augmented in the inferior Rolandic area prior to and during syllable-articulation with the onset and peak occurring earlier in the left side. Subsets of the inferior Rolandic sites, more frequently on the left side, showed differential gamma-augmentation elicited by articulation of phoneme [f] more than [h] or phoneme [i:] more than [alpha:]. Our observations suggest that the superior temporal gyrus may be active when externally presented or articulated auditory stimuli are present, and may be minimally active when articulation is about to be initiated. Our novel observation of phoneme-specific differential gamma-augmentation in the inferior Rolandic area may be partially attributed to the mouth position during phoneme-articulation. Our observations support the hypothesis that positioning of the mouth to articulate phonemes is predominantly driven and/or monitored by the primary sensorimotor area on the left side.


Subject(s)
Brain Mapping , Brain/physiology , Language , Speech Perception/physiology , Speech/physiology , Adolescent , Child , Electroencephalography , Epilepsy/physiopathology , Female , Humans , Image Interpretation, Computer-Assisted , Magnetic Resonance Imaging , Male
19.
Neuroimage ; 45(2): 477-89, 2009 Apr 01.
Article in English | MEDLINE | ID: mdl-19135157

ABSTRACT

Using intracranial electrocorticography, we determined how cortical gamma-oscillations (50-150 Hz) were induced by different visual tasks in nine children with focal epilepsy. In all children, full-field stroboscopic flash-stimuli induced gamma-augmentation in the anterior-medial occipital cortex (starting on average at 31 ms after stimulus presentation) and subsequently in the lateral-polar occipital cortex; minimal gamma-augmentation was noted in the inferior occipital-temporal cortex; occipital gamma-augmentation was followed by gamma-attenuation in three children. Central-field picture-stimuli induced sustained gamma-augmentation in the lateral-polar occipital cortex (starting on average at 69 ms) and subsequently in the inferior occipital-temporal cortex in all children and in the posterior frontal cortex in three children; the anterior-medial occipital cortex showed no gamma-augmentation but rather gamma-attenuation. Electrical stimulation of the anterior-medial occipital cortex induced a phosphene in the peripheral-field or eye deviation to the contralateral side, whereas that of the lateral-polar occipital cortex induced a phosphene in the central-field. In summary, full-field, simple and short-lasting visual information might be preferentially processed by the anterior-medial occipital cortex, and subsequently by the lateral-polar occipital cortex. Gamma-attenuation following augmentation in the striate cortex might be associated with a relative refractory-period to flash-stimuli or feed-forward inhibition by other areas. Central-field complex visual information might be processed by a network involving the lateral-polar occipital cortex and the inferior occipital-temporal cortex. A plausible interpretation of posterior frontal gamma-augmentation during central-field picture stimuli includes activation of the frontal-eye-field for visual searching. Gamma-attenuation in the anterior-medial occipital cortex during central-field picture-stimuli might be associated with relative inattention to the peripheral visual field during central-field object visualization.


Subject(s)
Biological Clocks , Cerebral Cortex/physiopathology , Electrocardiography/methods , Epilepsy/physiopathology , Evoked Potentials, Visual , Photic Stimulation/methods , Adolescent , Brain Mapping , Child , Child, Preschool , Female , Humans , Male , Stroboscopy/methods
20.
Brain ; 131(Pt 7): 1793-805, 2008 Jul.
Article in English | MEDLINE | ID: mdl-18508784

ABSTRACT

Recent studies have suggested that cortical gamma-oscillations are tightly linked with various forms of physiological activity. In the present study, the dynamic changes of intracranially recorded median-nerve somatosensory-evoked potentials (SEPs) and somatosensory-induced gamma-oscillations were animated on a three-dimensional MR image, and the temporal and spatial characteristics of these activities were analysed in 10 children being evaluated for epilepsy surgery. Visual and quantitative assessments revealed that short-latency SEPs and somatosensory-induced gamma-oscillations predominantly involved the post-central gyrus and less intensely involved the pre-central gyrus and the anterior parietal lobule. Formation of a dipole of N20 peak with opposite polarities across the central sulcus was well delineated in animation movies. High-frequency (100-250 Hz) somatosensory-induced gamma-oscillations emerged in the post-central gyrus at 13.6-17.5 ms after median-nerve stimulation, gradually slowed down in frequency around and below 100 Hz, and progressively involved the neighbouring areas. A substantial proportion of somatosensory-induced gamma-oscillations was initially phase-locked and the proportion of a non-phase-locked component gradually increased over time. The primary motor hand areas proven by cortical stimulation frequently coincided with the sites showing the largest N20 peak and the largest somatosensory-induced gamma oscillations. In vivo animation of SEPs and somatosensory-induced gamma oscillations both may be utilized to localize the primary sensory-motor hand area in pre-surgical evaluation. The dipole on SEPs is consistent with the previously accepted notion that the cortices along the central sulcus are activated. The high-frequency somatosensory-induced gamma-oscillations in the post-central gyrus may represent the initial neural processing for external somatosensory stimuli, whereas the subsequent lower-frequency oscillations might represent the reafferent cortical activity occurring in larger cortical networks.


Subject(s)
Epilepsy/physiopathology , Evoked Potentials, Somatosensory , Median Nerve/physiopathology , Adolescent , Adult , Brain Mapping/methods , Child , Child, Preschool , Electric Stimulation/methods , Electroencephalography/methods , Epilepsy/surgery , Female , Humans , Imaging, Three-Dimensional/methods , Infant , Male , Reaction Time , Signal Processing, Computer-Assisted , Somatosensory Cortex/physiopathology
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