• 한국컴퓨터정보학회논문지
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• 제23권12호
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• pp.21-26
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• 2018

As the large amount of data can be efficiently stored, the methods extracting meaningful features from big data has become important. Especially, the techniques of converting high- to low-dimensional data are crucial for the 'Data visualization'. In this study, principal component analysis (PCA; linear dimensionality reduction technique) and Isomap (non-linear dimensionality reduction technique) are introduced and applied to neural big data obtained by the functional magnetic resonance imaging (fMRI). First, we investigate how much the physical properties of stimuli are maintained after the dimensionality reduction processes. We moreover compared the amount of residual variance to quantitatively compare the amount of information that was not explained. As result, the dimensionality reduction using Isomap contains more information than the principal component analysis. Our results demonstrate that it is necessary to consider not only linear but also nonlinear characteristics in the big data analysis.

• Investigative Magnetic Resonance Imaging
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• 제13권1호
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• pp.40-46
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• 2009

목적 : 기능적 뇌 자기공명영상 (fMRI)과 확산텐서영상(DTI) 합성기법을 이용하여 피질척수로의 여러 부위에서 정량적 특성을 연구하고자 하였다. 대상 및 방법 : 신경학적 이상이 없는 정상인 10명 (남: 8, 여: 2, 평균연령: 30세, 연령분포 : 22 -38세)을 대상으로 하였다. fMRI는 1.5T를 이용하였으며, 손의 쥐기 펴기를 수행하였다. fMRI와 확산텐서섬유로(DTT)의 합성이 가능한 DtiStudio 프로그램을 이용하여 피질척수로를 3차원 영상화하였다. 이때, 시작 관심영역은 2차원 분할 비등방성(fractional anisotropy, FA) 색지도(color map)에서 fMRI의 운동 수행 시 활성부위가 가장 많은 곳으로, 목표 관심영역은 하부 전방 뇌교의 피질척수 부위로 설정하였다. 정량적 분석을 위하여 관심영역을 부채살부터 연수까지 좌우 각각 5곳에 설정하여 분할 비등방성과 현성 확산계수(ADC)를 측정하였다. 결과 : 모든 대상자는 fMRI에서 일차 감각운동 영역이 주로 활성화되었다. 확산텐서 영상에서 피질척수로의 경로는 일차 감각운동 영역부터 연수까지 주행하였다. 피질척수로의 FA 값은 모든 대상자에서 중뇌와 내측 섬유띠의 후지가 타 부위보다 높았다. 결론 : fMRI와 DTT의 합성기법은 피질척수로 상태의 3차원 영상화 및 각 부위에서 FA와 ADC값을 이용한 정량적 분석이 가능하였다. 앞으로, fMRI와 DTT 합성기법은 뇌손상 환자에서 피질척수로의 명확한 상태를 연구하는 데 유용하게 이용될 것으로 사료된다.

• Journal of Korean Neurosurgical Society
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• 제54권6호
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• pp.453-460
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• 2013

Objective : There is a rich literature confirming the default mode network found compatible with task-induced deactivation regions in normal subjects, but few investigations of alterations of the motor deactivation in patients with intracranial lesions. Therefore, we hypothesized that an intracranial lesion results in abnormal changes in a task-induced deactivation region compared with default mode network, and these changes are associated with specific attributes of allocated regions. Methods : Blood oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI) during a motor task were obtained from 27 intracranial lesion patients (mean age, 57.3 years; range 15-78 years) who had various kinds of brain tumors. The BOLD fMRI data for each patient were evaluated to obtain activation or deactivation regions. The distinctive deactivation regions from intracranial lesion patients were evaluated by comparing to the literature reports. Results : There were additive deactivated regions according to intracranial lesions : fusiform gyrus in cavernous hemangioma; lateral occipital gyrus in meningioma; crus cerebri in hemangiopericytoma; globus pallidus, lateral occipital gyrus, caudate nucleus, fusiform gyrus, lingual gyrus, claustrum, substantia nigra, subthalamic nucleus in GBM; fusiform gyrus in metastatic brain tumors. Conclusion : There is increasing interest in human brain function using fMRI. The authors report the brain function migrations and changes that occur in patients with intracranial lesions.

• Journal of Acupuncture Research
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• 제21권2호
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• pp.57-71
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• 2004

Objective : Physiological evidence regarding acupuncture's effect in human patients is not yet well established, despite considerable evidence for its therapeutic efficacy. Besides target or disease specificity of acupuncture, acupuncture analgesia (AA) appears to be another large subclass that poses many questions, such as whether there is point specificity with respect to which acupoint is most effective for a particular condition. Methods : We observed brain activation with functional magnetic resonance imaging (fMRI) using a set of stimuli that consist of pain, pain following Meridian acupuncture, and pain following Sham acupuncture. Results : Among the new observations, the most interesting fact is that data sets of both Meridian acupuncture and Sham acupuncture show decreased activation of the same brain areas related to the pain processing signals. Present functional MRI study demonstrate two important biological observations that could elucidate AA mechanism in human participants: the effects of acupuncture occur through mediation of the higher brain areas. Sham acupuncture stimulation appears to be almost as effective as traditional Meridian acupoint stimulation, suggesting that acupuncture is not entirely point specific. Decreased activation in the limbic paleo cortical areas appears to be the probable neurological manifestation of AA and strongly implies that acupuncture stimulation inhibits the transmission of ascending pain signals to the higher cortical areas by the previously known descending pain inhibitory circuit. Conclusion : We, therefore, a hypothesized that this pain inhibitory circuit is initiated and mediated via the broad sense Hypothalamus Pituitary Adrenal (BS HPA) axis in conjunction to the "sensory stimulation."

• Investigative Magnetic Resonance Imaging
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• 제13권1호
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• pp.47-53
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• 2009

목적: 기능적 자기 공명 영상을 이용하여 운동, 감각, 단어만들기, 듣고이해하기, 그리고 기억하기 등의 자극을 주어 소뇌 활성화를 평가하는 것이다. 대상 및 방법: 11명의 건강한 오른손잡이 지원자 (남: 여, 6:5, mean age: 27.4세)를 대상으로 1.5T 자기공명영상기기의 BOLD기법을 이용하여 뇌 전체를 축상면으로 기능적 자기공명영상을 얻었고 패러다임은 5번의 자극과 휴식을 반복 사용하였다. 왼쪽 손가락의 복잡한 운동, 감각 자극, 단어만들기, 듣고이해하기, 그리고 기억하기를 활성화 자극으로 사용하였고, 한계치는 p = 0.001를 사용하여, 소뇌 내 활성화를 SPM 5를 이용하여 활성화된 영역의 부위와 활성화정도를 평가하였다. 결과: 소뇌 활성화는 운동, 단어만들기, 그리고 기억하기에서 관찰되었다. 운동 자극에서는 949 영역이 활성화되었고 평균반응정도는 0.68이었고 단어만들기 자극에서는 319 영역이 활성화되었고 평균반응정도는 0.15이었으며 기억자극에서는 330의 영역이 활성화되었고 평균반응정도는 0.26이었다. 결론: 소뇌는 운동, 단어만들기, 그리고 기억하기등 다양한 기능적 자극에 관련이 되어 있으며, 이중에서도 운동기능에 가장 연관이 있었다. 기능적 자기 공명 영상은 소뇌 기능 연구하는 방법으로 이용이 가능할 것이다.

• 한국전문물리치료학회지
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• 제9권3호
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• pp.67-76
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• 2002

We report the reorganization of motor network resulted from intensive unilateral coordination training and the effect of cross education on the untrained side in patient with traumatic brain injury using functional magnetic resonance imaging (fMRI). A 22 year-old male patient who had suffered from diffuse axonal injury for 58 months showed coordination deficit in the left hand at initial examination. Intensive motor training including complex finger movements and coordination activities using a metronome was introduced to the patient 4 hours per day for a week. FMRI was performed on a 3T ISOL Forte scanner. All functional images were analyzed using SPM-99 software. Hand function was improved after training not only in the trained left hand, but also in the untrained right hand. There was no activation in the right primary motor area (M1) during left hand movement before training whereas robust activation of left M1 was demonstrated by the right hand movement. Profuse activation of bilateral prefrontal lobes was seen during both hand movements before training. After training of left hand, right M1 became prominently activated during the left hand motion. The activation of bilateral prefrontal lobes disappeared after training not only for the left hand movement but also for the right, which clearly demonstrated the effect of cross education. This case report demonstrated the learning-dependent reorganization of the M1 and the effect of cross education.

• 한국정밀공학회지
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• 제23권1호
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• pp.209-215
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• 2006

The present study purposed to examine differences between 20s and 40s in visuospatial performance, the number of activated yokels and cerebral lateralization using functional Magnetic Resonance Imaging (fMRI). For this study, eight college students in their twenties (21.5 years on the average) and six adults in their forties (45.7 years on the average) participated in the experiment. Functional brain images were taken from 37 MRI using the single-shot EPI method. Compared to the twenties the forties showed lower visuospatial performance and longer reaction time. In addition, compared to the twenties the forties had a smaller number of activated yokels and less cerebral lateralization. The results of this study show that people's visuospatial performance and number of activated yokels decrease with aging. In addition, they also suggest that cerebral lateralization decreases in order to supplement the lowering of visuospatial performance, which in turn symmetrizes the activation of the left and right hemisphere.

• 감성과학
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• 제18권2호
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• pp.55-64
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• 2015

The aim of the study was to investigate the neural substrates associated with processing anger among young males with alcohol use disorders (AUDs) using functional magnetic resonance imaging (fMRI). Eighteen individuals with AUD and 15 demographically similar non-abusers participated in the study. Participants were scanned on their brain functioning while they viewed an audio-visual film clip that was previously designed specifically to induce anger emotion, followed by anpsychological assessment. Greater brain activities were detected in the left inferior frontal gyrus (IFG) and dorsal anterior cingulate cortex (dACC) among subjects with AUD compared to the controls during the exposure to anger-provoking stimuli. Despite the same level of subjective anger during anger induction, the greater activations both in the IFG and dACC regions may suggestthat individuals with AUD have a greater propensity to undergo cognitive control and self-regulation while experiencing anger.

• 한국음향학회:학술대회논문집
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• 한국음향학회 2002년도 하계학술발표대회 논문집 제21권 1호
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• pp.313-316
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• 2002

본 연구에서는 기능적 자기공명 영상법(functional magnetic resonance imaging)을 이용하여, 한국어, 일어, 프랑스어, 영어 등 여러 언어를 구사할 수 있는 다중언어화자들을 대상으로 각 언어에 따른 대뇌 언어처리 과정을 알아보고, 그 처리과정이 해당언어의 유창성, 습득시기에 따라 어떻게 달라지는지를 알아보았다. 실험 결과, 언어처리에 있어 핵심적인 역할을 하는 것으로 보고되는 Broca 영역은 언어의 이해와 산출 과정에 모두 관계된 것으로 보이며, 언어의 산출과정에는 언어의 이해과정에 관계되는 영역외에 조음과정에 따른 영역의 활성화가 보고되었다. 또한 언어습득시기와 유창성에 따른 각 언어의 활성화를 살펴보면, 유창성이 높을수록 대뇌 활성화는 줄어들며, 유창성이 낮은 언어조건에서는 언어처리 영역의 활성화 수준이 높아지며 또한 우반구 및 전전두회(prefrontal gyrus)의 활성화가 높아지는 것이 보인다.

• 스마트미디어저널
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• 제5권1호
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• pp.30-37
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• 2016

In recent decades, the study of human brain function has dramatically increased thanks to the advent of Functional Magnetic Resonance Imaging. This is a powerful tool which provides a deep view of the activities of the brain. From fMRI data, the neuroscientists analyze which parts of the brain have responsibility for a particular action and finding the common pattern representing each state involved in these tasks. This is one of the most challenges in neuroscience area because of noisy, sparsity of data as well as the differences of anatomical brain structure of each person. In this paper, we propose the use of appropriate discriminant methods, such as Fisher Discriminant Ratio and hypothesis testing, together with strong boosting ability of Adaboost classifier. We prove that discriminant methods are effective in classifying cognitive states. The experiment results show significant better accuracy than previous works. We also show that it is possible to train a successful classifier without prior anatomical knowledge and use only a small number of features.