• Clinical and Experimental Pediatrics
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• v.52 no.1
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• pp.99-104
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• 2009

Purpose : Magnetic resonance diffusion tensor imaging-based three-dimensional fiber tractography (DTI-FT) is a new method which demonstrates the orientation and integrity of white matter fibers in vivo. However, clinical application on children with cerebral palsy is still under investigation. We present various abnormal patterns of DTI-FT findings and accordance rate with clinical findings in children with hemiplegic cerebral palsy, to recognize the use fulness of DTI-FT. Methods : The thirteen children with hemiplegic cerebral palsy evaluated at Yeungnam University hospital from March, 2003 to August, 2007 were enrolled in this study and underwent magnetic resonance DTI-FT of the corticospinal tracts. Two regions of interest (ROI) were applied and the termination criteria were fractional anisotropy ${\geq}0.3$, angle ${\leq}70^{\circ}$. Results : The patterns and distribution of abnormal DTI-based corticospinal tractographic findings were interruption(10 cases, 76.9%), reduction of fiber volume (8 cases, 61.5%), agenesis of corticospinal tract (3 cases, 23.1%), transcallosal fiber (2 cases, 15.4%) and, aberrant corticospinal tracts (4 cases, 30.8%). Abnormal DTI-based corticospinal tractographic findings were in accordance with the clinical findings of cerebral palsy in 84.6% of the enrolled patients. Conclusion : Our results suggest that DTI-FT would be a use ful modality in the assessment of the corticospinal tract abnormalities in children with hemiplegic cerebral palsy.

• Journal of Biomedical Engineering Research
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• v.22 no.2
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• pp.145-150
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• 2001

대뇌 피질에 삽입하여 깊이에 따라 신경 신호를 기록하기 위한 탐침형 반도체 미세전극 어레이(depth-type silicon microelectrode array, 일명 SNU probe)를 제작하였다. 붕소를 확산시켜 생성된 고농도 p-type doping된 p＋ 영역을 습식식각 정지점으로 사용하는 기존의 방법과 달리 실리콘 웨이퍼의 앞면을 건식식각하여 원하는 탐침 두께만큼의 깊이로 트렌치(trench)를 형성한 후 뒷면을 습식식각하는 방법으로 탐침 형태의 미세 구조를 만들었다. 제작된 반도체 미세전극 어레이의 탐침 두께는 30 $\mu\textrm{m}$이며 실리콘 건식식각을 위한 마스크로 6 $\mu\textrm{m}$ 두께의 LTO(low temperature oxide)를 사용하였다. 탐침의 두께는 개발된 본 공정을 이용해서 5~90 $\mu\textrm{m}$ 범위까지 쉽게 조절할 수 있었다. 탐침의 두께를 보다 쉽게 조절할 수 있게 됨에 따라 여러 신경조직에 필요한 다양한 구조의 반도체 미세전극 어레이를 개발할 수 있게 되었다. 본 공정을 이용해서 개발된 4채널 SUN probe를 사용하여 흰쥐의 제1차 체감각 피질에서 4채널 신경 신호를 동시에 기록하였으며, 전기적 특성검사에서 기존의 탐침형 반도체 미세전극, 텅스텐 전극과 대등하거나 우수한 신호대 잡음비(signal to noise ratio, SNR)특성을 가짐을 확인하였다.

• Proceedings of the Optical Society of Korea Conference
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• 2008.02a
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• pp.455-456
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• 2008

근적외선 분광법(Near-infrared spectroscopy, NIRS)은 대뇌피질에서의 혈류변화(oxy-, deoxyhemoglobin의 농도변화)를 비침습적으로 측정할 수 있는 방법이다. 본 논문에서는 향후 뇌-컴퓨터 접속기술(Brain computer interface)에 적용하기위한 초기 연구단계로, 쥐의 수염을 자극시 활성화되는 대뇌수염피질 영역에서의 혈류변화 및 전기신호를 동시에 측정하고 두 신호의 패턴을 분석한다.

• Journal of Life Science
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• v.14 no.6 s.67
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• pp.975-985
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• 2004

This study attempts to investigate the developmental alterations of rat cerebral cortex, and the effects of EGEE on the developmental cerebral cortex in the prenatal, postnatal and adults were examined by morphological methods and H-E staining was used for the histological changes. In the case of injection of EGEE, at 14 day of fetal phase, parietal cortex was thickest $(95{\pm}12.7\;{\mu}m)$ but, it was thinner than in the control group $(102{\pm}14.0\;{\mu}m)$ and, occipital cortex $(57{\pm}10.5\;{\mu}m)$ compared with other cortexes was the thinnest in fetal phase. In the suckling phase, each cortex grew thick quickly but, after weanning phase, the growth of the cortex slowed and the thickness of cortex was similar to that of cortex in the adult phase. At 105 day after birth, the parietal cortex was thickest $(934{\pm}21.6\;{\mu}m)$ but, decreased compared with control group $(1113{\pm}19.0\;{\mu}m)$. When EGEE was injected in intraperitoneal of rat, the number of neuroblasts per unit area was largest $(207.7{\pm}11.4/10^{-2}\;mm$ at the mantle layer of parietal cortex at 14 day of fetal phase but, decreased compared with control group $(224.2{\pm}13.8/10^{-2}\;mm$ , and the size was largest $(7.5{\pm}1.3\;{\mu}m)$ at the ependymal cell layer of occipital cortex at 3 day after birth but, decreased compared with control group $(9.0{\pm}1.2\;{\mu}m)$. Simillar to control group, the number of granular cells and pyramidal cells were largest at the II and III layer of parietal cortex, but decreased during developmental phase. The size was largest at the IV and V layer of occipital cortex but it was decreased compared with control group. When EGEE was injected in intraperitoneal of rat, the cerebral cortex from fetal phase to 3 day after birth has differentiated into the 3 layers; ependymal, mantle and marginal layer, but empty cisternaes or vacoules in the cerebral cortexes and the condensed phases of neuroblasts were appeared. From 5 day after birth, it has differentiated into the 4 layers; molecular, external granular, mixed layer of internal granular, external and internal pyramidal cells and multiformal layer but, empty cisternaes or vacoules in the granular and pyramidal cell layers were appeared and the number per unit area of neuron was decreased. In the cerebral cortex of the weaning and adult phases, division of cell layers was not clear and empty cisternae was formed in the cortex with the cells in external granular and pyramidal cell layers, was magnified or condensed around blood vessels of neurons.

• Korean Journal of Cognitive Science
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• v.28 no.4
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• pp.267-297
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• 2017

The anatomical structure of the brain reflects a great amount of information about an individual's cognitive ability. The present study reviewed research on developmental changes in brain structure in relation to biological maturation and intellectual growth focusing on children and adolescents. The purpose of the present study was to achieve an understanding of how children and adolescents' brain matures with development and also to examine whether individual differences in intelligence influences the development of brain structure. The first section introduces methods of measurement and analysis of brain structure, such as voxel-based morphometry and structural covariance. The second section reviews studies on the biological maturation of the brain and variables that influence brain development such as sex, environmental factors, and mental disorders, etc. The third section introduces the Parieto-Frontal Integration Theory of intelligence and reviews studies on the association between intelligence and developmental changes of the brain, including changes in structural covariance and functional connectivity. We conclude with a discussion on educational/clinical implications of this work and directions for future studies.

• Journal of the Korean Society of Radiology
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• v.8 no.4
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• pp.163-170
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• 2014

This study is to investigate neuro-anatomical correlation between neuropsychological results and cerebral cortex thickness of cognitive ability in the brain MRI targeting the patients with mild cognitive impairment. It was that 78 people who were diagnosed as first Parkinson's disease followed by neuropsychological screening battery(Parkinson's disease with mild cognitive impairment: 39 people; Parkinson's disease with normal cognition: 39 people) and 32 people of normal group were selected. Correlation between mild cognitive impairment and normal cognitive impairment and correlation between neuropsychological screening battery and cerebral cortex thickness in the brain MRI were performed by independent sample t-test or Pearson correlation coefficient and then level of significance of collected data was verified in p<0.05. As a result, cerebral cortex thickness of the Parkinson's disease with mild cognitive impairment in both side precuneas and right inferiortemporal lobe had statistically significant decrease. In addition, function of visuospatial ability, verbal and visual memory was reduced in neuropsychological screening battery for cognitive assessment. Especially, there was correlation between neuropsychological screening battery of verbal and visual memory anatomical left precuneus.

• Korean Journal of Biological Psychiatry
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• v.5 no.2
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• pp.184-196
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• 1998

With a rapid development of neuroscience, the theories related to the pathophysiology of schizophrenia have been changed a lot from a simple hyperdopaminergic one to the various complicated ones. Among these, the theories regarding prefrontal cortex(PFC) pathology as a cause of schizophrenia are gaining more recognition as the results of neuroimaging and neuropsychological tests in schizophrenia consistently report abnormalities in PFC. Therefore, we first reviewed the unique characteristics of PFC in anatomy, neurochemistry and neurophysiology to enhance an understanding of those ones. Secondly, various neurotransmitter, neurodevelopmental and neural network theories of schizophrenia introduced recently were reviewed in terms of PFC pathology.

• Journal of Dental Rehabilitation and Applied Science
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• v.25 no.2
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• pp.109-123
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• 2009

The aim of the study was to assess the influence of insertion torque of bone quality and to compare axial force, moment and von Mises stress using finite element analysis of plastoelastic property for bone stress and strain by dividing bone quality to its thickness of cortical bone, density of trabecular bone and existence of lower cortical bone when implant inserted to mandibular premolar region. The $Br{\aa}nemark$ MKIII. RP implant and cylindrical bone finite model were designed as cortical bone at upper border and trabecular bone below the cortical bone. 7 models were made according to thickness of cortical bone, density of trabecular bone and bicortical anchorage and von Mises stress, axial force and moment were compared by running time. Dividing the insertion time, it seemed 300msec that inferior border of implant flange impinged the upper border of bone, 550msec that implant flange placed in middle of upper border and 800msec that superior border of implant flange was at the same level as bone surface. The maximum axial force peak was at about 500msec, and maximum moment peak was at about 800msec. The correlation of von Mises stress distribution was seen at both peak level. The following findings were appeared by the study which compared the axial force by its each area. The axial force was measured highest when $Br{\aa}nemark$ MKIII implant flange inserts the cortical bone. And maximal moment was measured highest after axial force suddenly decreased when the flange impinged at upper border and the concentration of von Mises stress distribution was at the same site. When implant was placed, the axial force and moment was measured high as the cortical bone got thicker and the force concentrated at the cortical bone site. The influence of density in trabecular bone to axial force was less when cortical bone was 1.5 mm thick but it might be more affected when the thickness was 0.5 mm. The total axial force with bicortical anchorage, was similar when upper border thickness was the same. But at the lower border the axial force of bicortical model was higher than that of monocortical model. Within the limitation of this FEA study, the insertion torque was most affected by the thickness of cortical bone when it was placed the $Br{\aa}nemark$ MKIII implant in premolar region of mandible.

• The korean journal of orthodontics
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• v.40 no.3
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• pp.167-175
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• 2010

Objective: The aim of this study was to validate the Periotest values for the prediction of orthodontic mini-implants' stability. Methods: Sixty orthodontic mini-implants (7.0 mm $\times$ $\emptyset1.45$ mm; ACR, Biomaterials Korea, Seoul, Korea) were inserted into the buccal alveolar bone of 5 twelve month-old beagle dogs. Insertion torque (IT) and Periotest values (PTV) were measured at the installation procedure, and removal torque (RT) and PTV were recorded after 12 weeks of orthodontic loading. To correlate PTV with variables, the cortical bone thickness (mm) and bone mineral density (BMD) within the cortical bone and total bone area were calculated with the help of CT scanning. Results: The BMD and cortical bone thickness in mandibular alveolus were significantly higher than those of the maxilla (p < 0.05). The PTV values ranged from -3.2 to 4.8 for 12 weeks of loading showing clinically stable mini-implants. PTV at insertion was significantly correlated with IT (-0.51), bone density (-0.48), cortical bone thickness (-0.42) (p < 0.05) in the mandible, but showed no correlation in the maxilla. PTV before removal was significantly correlated with RT (-0.66) (p < 0.01) in the mandible. Conclusions: These results show that the periotest is a useful method for the evaluation of mini-implant stability, but it can only be applied to limited areas with thick cortical and high density bone such as the mandible.

• Progress in Medical Physics
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• v.17 no.3
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• pp.159-166
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• 2006

The nonlinearity of hemodynamic response in the somatosensory cortex was investigated with vibrotactile stimulation. The stimuli consisted of a train of 25 Hz, each tasting five different duration periods, 2 s, 4 s, 8 s 12 s, or 16 s with 20 sec periods of no vibration in a pseudo-random order. In order to understand the linearity on the change of stimulus duration for somatosensory cortex, two different tests- checking the linearity of system and finding the impulse response function from gamma-variate function were applied to analyze the hemodynamic response functions. They have produced nearly same results. The BOLD response in the somatosensory cortex Is nonlinear for stimuli of less than 8 seconds, but nearly linear for stimuli greater than 8 seconds. The amplitude, area, TTP, and FWHM as functions of the stimulus duration were calculated and showed a significant downward trend with Increasing stimulus duration for the amplitude and the area. It supports the ranges of nonlinearity are less than 8 seconds.