• Investigative Magnetic Resonance Imaging
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• v.7 no.1
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• pp.56-60
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• 2003

We present MR diffusion-weighted imaging (DWI) findings of status epilepticus in two patients. DWI showed a focal or diffuse hyperintensity with decreased apparent diffusion coefficient (ADC) value, indicating cytotoxic edema in th e cerebral hemispheric cortices. The hyperintensities were located in the bilateral temporoparietooccipital areas and insular cortex in one patient, and unilaterally in the temporal lobe in the other patient.

• The Korean Journal of Nuclear Medicine
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• v.34 no.1
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• pp.10-21
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• 2000

Purpose: Episodic memory is described as an 'autobiographical' memory responsible for storing a record of the events in our lives. We performed functional brain activation study using ${H_2}^{15}O$ PET to reveal the neural basis of the encoding and the retrieval of episodic memory in human normal volunteers. Materials and Methods: Four repeated ${H_2}^{15}O$ PET scans with two reference and two activation tasks were performed on 6 normal volunteers to activate brain areas engaged in encoding and retrieval with verbal materials. Images from the same subject were spatially registered and normalized using linear and nonlinear transformation. Using the means and variances for every condition which were adjusted with analysis of covariance, t-statistic analysis were performed voxel-wise. Results: Encoding of episodic memory activated the opercular and triangular parts of left inferior frontal gyrus, right prefrontal cortex, medial frontal area, cingulate gyrus, posterior middle and inferior temporal gyri, and cerebellum, and both primary visual and visual association areas. Retrieval of episodic memory activated the triangular part of left inferior frontal gyrus and inferior temporal gyrus, right prefrontal cortex and medial temporal area, and both cerebellum and primary visual and visual association areas. The activations in the opercular part of left inferior frontal gyrus and the right prefrontal cortex meant the essential role of these areas in the encoding and retrieval of episodic memory. Conclusion: We could localize the neural basis of the encoding and retrieval of episodic memory using ${H_2}^{15}O$ PET, which was partly consistent with the hypothesis of hemispheric encoding/retrieval asymmetry.

• The Korean Journal of Nuclear Medicine
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• v.33 no.3
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• pp.247-261
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• 1999

Purpose: The aim of this study was to evaluate the normal values of regional cerebral blood flow (rCBF) and cerebrovascular reserve (CVR) in normal children to aged volunteers using Tc-99m HMPAO, Materials and Methods: Thirty four right-handed normal volunteers (20 males, 14 females, mean age $40.3{\pm}24.9$ years, range 4 to 82 years) were underwent rost/acetazolamide (ACZ) brain SPECT using Tc-99m HMPAO and the sequential injection and subtraction method. rCBF was estimated on the basis of a semiquantitative approach by means of right/left ratio, region/cerebellum and region to whole brain ratios in (rental, parietal, temporal, and occipital lobes, basal ganglia, thalami, and cerebellum. CVR was measured by means of % perfusion increase calculated as % mean count change compared to rest rCBF in each regions. Results: Mean values of right to left ratios range from 1.004 to 1.018, rCBF was highest in cerebellum and lowest in basal ganglia and thalami. Frontal and temporal rCBF decreased while occipital and thalamic rCBF increased according to age. No sexual difference of rCBF was noted. Mean CVR was $29.9{\pm}12.9%$. Mean CVR significantly increased to late teens, and declined thereafter. After 6th decade, CVR in both frontal lobes, left parietal lobe and right basal ganglia decreased significantly with advancing age. There was no sexual difference of CVR. Conclusion: Quantitative assessment of CVR was possible by ACZ Tc-99m HMPAO brain SPECT. It revealed that rCBF and CVR changed according to age in normal Korean volunteers. There was no sexual difference.

• Investigative Magnetic Resonance Imaging
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• v.9 no.1
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• pp.16-23
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• 2005

Purpose : In order to investigate the functional brain anatomy associated with mental calculation, functional magnetic resonance imaging was performed. Materials and Methods : In six normal right handed subjects, functional MR images were obtained using a 1.57 MR scanner and the EPI BOLD technique. The study included experiment I and experiment II. Each experiment consisted of five resting and four activation periods with each period of 30 seconds. During the activation period of both experiment I and II, calculation equations[an example: $(4+5)\times8=72$] were presented and the subjects were instructed to decide true or false of them. During the resting period of experiment I, the subjects were instructed to visually fixate on a crosshair. During the resting period of experiment II, two diagrams (an example: $(\bullet,\;\blacksquare)$)were presented and the subjects were instructed to decide they are same or not. For the post-processing of images, the SPM program was used, with the threshold of significance set at p<0.00001. The activated areas during the tasks were assessed. Results : In experiment 1, the inferior frontal gyrus, prefrontal cortex, promoter area, supplementary motor area, and intraparietal sulcus including superior parietal cortex were activated bilaterally. Although these areas were also activated in experiment II, the activated signals in the right frontal and parietal lobes were lessened. Conclusion : The left inferior frontal gyrus and prefrontal cortex and bilateral intraparietal sulci were activated during mental calculation. The right frontal and parietal lobes might be related to attention and decision making.

• Investigative Magnetic Resonance Imaging
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• v.4 no.1
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• pp.52-57
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• 2000

Purpose : The purpose of this study was to investigate the pattern of cerebral response to motor tasks in patients with schizophrenia compared with normal subjects using functional MRI. Materials and methods ; Nine right handed-schizophrenic patients and six right-handed normal subjects were included. We used right hand movement as task. Series of 120 consecutive echo-planar images per section were acquired during three cycles of task and rest activations. Lateralization index of cortical response was measured and compared between patients and normal subjects. Results ; Right hand motor task was associated with greater activation in left sensorimotor cortex than the right in normal subjects. Schizophrenia patients showed relatively decreased activation in left cortex and increased activation in right cortex compared with normal subjects. In one patient, reversed lateralization was noted. Conclusion : Normal hemispheric asymmetry of cortical response to motor task was found in different pattern in schizophrenia. Our result is consistent with functional disturbance of motor circuitry in this disorder. Functional MRI will play an important role in diagnosis and research of this disorder.

• Radiation Oncology Journal
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• v.16 no.2
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• pp.125-138
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• 1998

Purpose : To evaluate the late effect(3 and 6 months) of cis-diarnrninedichlo-roplatinum(II)(cisplatin) on the radiation brain damage when the cisplatin was intraperitoneally infused immediately after whole brain irradiation in the rats. Materials and Methods : The histolopathological findings of the brain were examined in rat brains at 3 and 6 months after the treatment. The rats were irradiated(20 or 22.5 Gy, RT) or cisplatin was injected intraperitoneally(2,4, or 8mg/kg, CT) and in combined treatment group, cisplatin(2mg/kg) was injected immediately after irradiation(20 or 22.5 Gr). Histopathological examination was done mostly in irradiation or cisplatin alone groups, because the rats in combined group died during experimental period except 2 rats. Results : The rats treated with cisplatin showed marked epithelial vacuolation with perivascular edema and vascular dilatation in choroid plexus at 3 months as well as multifocal necrosis involving fimbria and cerebellar hemispheres at 3 and 6 months. The changes were more prominent in rats with 2mg/kg injection compared to rats with 8mg/kg injection. The rats with RT and combined CT and RT showed characteristic delayed irradiation effects such as focal coagulation necrosis and vascular changes, which were more marked than previous reports Prominent perivascular and leptomenin-geal astrocytic Proliferation was well documented by anti-GFAP antibody. Cisplatin treatment did not enhance the effect of radiation-induced changes of blood vessels and astrocytic proliferation. Conclusion : The focal necrosis was the most consistently noted finding in this study, it suggested the possibility to use this as an evaluation factor for combined effects of RT and cisplatin.

• Investigative Magnetic Resonance Imaging
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• v.14 no.2
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• pp.126-133
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• 2010

Purpose : The study was to evaluate the localization of the abnormal gyral and sulcal patterns obtained by means of brain surface rendering imaging. Materials and Methods : Nineteen patients with cortical dysplasia who underwent brain surface rendering MR imaging were included in this study. We acquired MP-RAGE sequence and created the 3-D surface rendering MR images by using $VoxelPlus^{(R)}$. Anatomical locations and configurations of abnormal gyri and sulci were reviewed. Results : Abnormal gyral and sulcal patterns were seen 18 in 19 patients. The configuration and orientation of affected gyri and sulci were clearly evaluated in the brain surface rendering images. In a lissencephaly, the a cortex was not delineated and showed markedly thick and smooth gyral pattern. In a schizencephaly, there were wheel shaped broad gyral pattern around the cleft. In a hemimegalencephaly, an affected hemisphere were enlarged and displayed thick and wide gyral pattern. In CBPS, the insular cortex was exposed and the gyri of the lesion were thickened. In focal cortical dysplasia, there were irregular serrated or thick and enlarged gyri. Conclusion : Brain surface rendering MR imaging is useful for the evaluation of a detailed gyral pattern and accurate involvement site of abnormal gyri.

• Korean Journal of Cognitive Science
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• v.22 no.4
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• pp.469-494
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• 2011

It is well known that visual objects belonging to the same perceptual category compete for category-specific, limited-capacity attentional resource. However, it remains to be seen how perceptually identical objects interact with each other during visual analyses. Perceptually identical objects might suppress each other as much as categorically identical objects do. Alternatively, they might cooperate to generate a perceptual representation which is long lasting and robust to noise. Such possibilities were tested in the current research with three behavioral experiments using the Stroop task. As results, relative to a single distractor, Stroop interference was diluted by two different distractors of a category while it was enhanced by two perceptually identical distractors (Experiment 1). This redundancy effect disappeared when two different distractors associated with the same response were presented (Experiment 2), and it was not affected by the between- vs. within-hemisphere distractor presentations (Experiment 3). These findings indicate that the redundancy effect of distractors may be mediated by perceptual representations based on hemisphere-independent attentional resources. Overall, the current study supports the hypothesis that Stroop interference is constrained by category-specific attentional resources and further suggests that redundant presentations of a stimulus overcome such attentional constraints by facilitating perceptual processing.

• Proceedings of the Korean Society for Cognitive Science Conference
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• 2002.05a
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• pp.216-221
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• 2002

본 연구는 문자 규칙 심층성이 다른 문자체계인 한국어와 중국어의 차이가 이중언어화자의 모국어 처리와 외국어 처리에서 각각 어떤 대뇌 활성화의 차이를 가져오는지 fMRI (functional Magnetic Resonance Imaging)를 이용하여 살펴보았다. 중국어 (Ll)-한국어(L2) 이중언어화자 및 한국어(Ll)-중국어(L2) 이중언어화자를 제 2언어 습득시기에 따라 초기 및 후기 이중언어화자로 구분하여 모국어 차이와 습득시기에 따른 영향을 알아보았다. 실험 1에서는 어휘 판단 과제(lexical decision task)를 실시하였고, 실험 2에서는 의미 판단 과제(semantic decision task)를 각각 실시하였다. 어휘판단과제를 사용한 실험 1의 결과는 음운처리와 관련된 좌반구 SMG(supramarginal gyrus), 하두정소엽(inferior parietal lobule, BA 39, 40)에서 중국어-한국어 초기 및 후기이중언어화자의 경우, 한국어 조건에서 보다 많은 활성화를 보였으나, 한국어-중국어 화자의 경우 활성화가 나타나지 않았다. 철자처리에 관련된 방추상회(fusiform gyrus, BA 37, 19) 영역에서는 중국어-한국어 화자뿐만 아니라, 한국어-중국어 인중언어화자의 경우도 중국어 조건에서 보다 많은 활성화를 보였다. 실험 2에서 사용한 의미판단과제의 경우, 중국어-한국어 이중언어화자의 경우 어휘판단과제를 사용한 실험 1의 결과에서 보고된 한국어 특정적인 반응, 즉 SMG영역에서의 활성화의 증가가 실험 2에서는 나타나지 않았다. 그러나 한국어-중국어 이중언어화자의 경우, 실험 1에서 나타난 것과 같이 철자처리 혹은 의미처리와도 관련된다고 보고되는 방추상회(fusiform gyrus)등의 영역 유의미한 차이를 나타났다. 이는 어휘 판단과제와 의미판단과제가 유도하는 뇌 활성화 양상이 다름을 시사한다. 종합해 볼 때, 이중언어화자의 뇌 영상 연구에서 어휘수준에서는 거의 공통적인 활성화를 보인다는 개략적 수준의 연구 결과를 넘어, 음운처리 및 철자처리와 같은 어휘접근 수준에서는 이중언어화자들의 뇌 활성화가 다르게 일어남을 보여주고 있다. 따라서 이중언어 화자의 뇌 기전을 밝히기 위해서도 보다 개략적 수준을 넘어 언어처리의 세부적인 수준에 따른 접근이 필요함을 시사한다.

• Pediatric Infection and Vaccine
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• v.30 no.2
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• pp.91-96
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• 2023

Infection with enterovirus (EV) 71 is usually associated with hand-foot-and-mouth disease and herpangina. The most frequent neurologic complication is brainstem encephalitis. A 30-month-old boy visited the pediatric emergency department with fever, lethargy, and abnormal eye contact. His mental status was slightly drowsy. On hospitalization day 2, the patient experienced respiratory arrest with apnea. Brain magnetic resonance imaging revealed bilateral symmetric T2-high signal lesions without enhancement in the posterior aspect of the brainstem and left medial temporal lobe. Electroencephalography was indicative of diffuse cerebral dysfunction with diffuse high amplitude and irregular delta activities. He underwent a gene study and was diagnosed with myoclonic epilepsy with ragged red fibers syndrome. We report a case of EV 71 brainstem encephalitis by polymerase chain reaction for nasopharyngeal aspirates and feces with rapid progression within one day of fever without the manifestation of throat and skin lesions because of his underlying mitochondrial disease.