• 대한의용생체공학회:의공학회지
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• 제42권6호
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• pp.295-303
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• 2021

Idiopathic normal-pressure hydrocephalus (INPH) is considered a potentially treatable neurological disorder by shunt surgery and characterized by a triad of symptoms including gait disturbance, cognitive impairment and urinary dysfunction. Although disorders of white matter are generally viewed as the principal pathological features of INPH, analysis of cortical features are important since the destruction of neural tracts could be associated with cortical structural changing. The aim of the study was to determine whether there was any relationship between gait parameter and structural features of cerebral cortex in INPH patients. Gait parameters were measured as follows: step width, toe in/out angle, coefficient of variation (CV) value of stride length, CV value of stride time. After obtaining individual brain MRI of patients with INPH and hemispheric cortical surfaces were automatically extracted from each MR volume, which reconstructed the inner and outer cortical surface. Then, cortical thickness, surface area, and volume were calculated from the cortical surface. As a result, step width was positively correlated with bilateral postcentral gyrus and left precentral gyrus, and toe in/out was positively correlated with left posterior parietal cortex and left insula. Also, the CV value of stride length showed positive correlation in the right superior frontal sulcus, left insula, and the CV value of stride time showed positive correlation in the right superior frontal sulcus. Unique parameter of cerebral cortical changes, as measured using MRI, might underline impairments in distinct gait parameters in patients with INPH.

• 대한의용생체공학회:의공학회지
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• 제27권2호
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• pp.64-72
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• 2006

The present study introduces a new cortical patch-based source model for EEG/MEG cortical source imaging to consider anatomical constraints more precisely. Conventional source models for EEG/MEG cortical source imaging have used coarse cortical surface mesh or sampled small number of vertices from fine surface mesh, and thus they failed to utilize full anatomical information which nowadays we can get with sub-millimeter modeling accuracy. Conventional ones placed a single dipolar source on each cortical patch and estimated its intensity by means of various inverse algorithms; whereas the suggested cortical patch-based model integrates whole cortical area to construct lead field matrix and estimates current density that is assumed to be constant in each cortical patch. We applied the proposed and conventional models to realistic EEG data and compared the results quantitatively. The quantitative comparisons showed that the proposed model can provide more precise spatial descriptions of neuronal source distribution.

• Journal of Korean Neurosurgical Society
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• 제30권11호
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• pp.1300-1307
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• 2001

Purposes : This study reports the possible causes of seizure recurrence in patients underwent previous epilepsy surgery, and surgical strategy for resection of the additional epileptogenic zone locating at the distant area to the site of first resection. Methods : A total of 10 patients with previous surgery due to intractable epilepsy were studied. Five of these underwent standard temporal lobectomy, four extratemporal resection, and one corticoamygdalectomy. Seizure outcome of these were class III-IV. Evaluation methods for reoperation included MRI, 3D-surface rendering of MRI, PET, prologned video-EEG recording with surface electrodes and subdural grid electrodes. Additional resection was done in the frontal lobe in two, in the temporal lobe in three, in the parietal lobe in two, and in the supplementary sensori-motor area in two. Tumor in the superior frontal gyrus in the left hemisphere was removed in one patient. Extent of resection was decided based on the results of ictal subdural grid EEGs and MRI findings. Awake anesthesia and electrocortical stimulation were performed in the two patients for defining the eloquent area. Results : Histopathologic findings revealed extratemporal cortical dysplasia in six, hippocampal sclerosis and cortical dysplasia of the temporal neocortex in one, neuronal gliosis in two, and meningioma in one. Previous pathology of the five patients with cortical dysplasia in the second operation was hippocampal sclerosis plus cortical dysplasia of the temporal neocortex. After reoperation, seizure outcomes were class I in six, class II in three, class III in one at the mean follow-up period of 17.5 months. Characteristically, patients in class II-III after reoperation showed histopathologic findings of hippocampal sclerosis plus temporal neocortical cortical dysplasia plus extratemporal cortical dysplasia. Conclusions : Seizure recurrence after epilepsy surgery was related with the presence of an additional epileptogenic zone distant to the site of first operation, and the majority of the histopathology of the surgical specimens was cortical dysplasia. In particular, hippocampal sclerosis plus temporal neocortical cortical dysplasia was highly related with seizure recurrence in patients with previous operation. In these patients, multimodal evaluation methods were necessary in defining the additional epileptogenic zone.

• 한국동물학회지
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• 제39권2호
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• pp.173-181
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• 1996

The time-course process by which spermatozoa penetrates through the micropvle apparatus into the egg cytoplasm of rainbow trout, Oncorhvnchus mvkiss, was examined with transmission and scanning electron microscopy. In the unfertilized egg, the ess surface beneath the inner opening of the micropylar canal did not differ distinctly from the rest of the animal pole area. A spermatozoon attached to the micropvle opening 20 seconds after insemination. In the initial stases of penetration, the spermatozoon still within the micropvlar canal attached perpendicularly at its apical tip to the ess surface, then the sperm head was rapidly engulfed by the folded egg surface with its manly microvilli. A large fertilization cone with microvillus-free surface appeared on the esS surface sutra-rounding the penetrating spermatozoon. The head portion of the penetrating spermatozoon was completely wrapped by the ess surface with only the tail portion visible externally 30 seconds after insemination. The fertilization cone displayed the tail portion of the penetrating spermatozoon on the central portion of its surface 60 seconds after insemination. 150 seconds after insemination, breakdown of the cortical granules elevation were initiated at the animal pole, then completed at the vegetable pole area. The spermatozoon disappeared from the outer surface of the ess before the fertilization cone completely retracted 250 seconds after insemination. In result, the block to polvspermv to permit entry of a sin81e sperm is considered to be mechanical by the rnorpholoSical design of the micropvle and fertilization cone.

• Korean Journal of Radiology
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• 제22권5호
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• pp.782-791
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• 2021

Objective: To evaluate the signal intensity of the periosteum using ultrashort echo time pulse sequence with three-dimensional cone trajectory (3D UTE) with or without fat suppression (FS) to distinguish from artifacts in porcine tibias. Materials and Methods: The periosteum and overlying soft tissue of three porcine lower legs were partially peeled away from the tibial cortex. Another porcine tibia was prepared as three segments: with an intact periosteum outer and inner layer, with an intact periosteum inner layer, and without periosteum. Axial T1 weighted sequence (T1 WI) and 3D UTE (FS) were performed. Another porcine tibia without periosteum was prepared and subjected to 3D UTE (FS) and T1 WI twice, with positional changes. Two radiologists analyzed images to reach a consensus. Results: The three periosteal tissues that were partially peeled away from the cortex showed a high signal in 3D UTE (FS) and low signal on T1 WI. 3D UTE (FS) showed a high signal around the cortical surface with an intact outer and inner periosteum, and subtle high signals, mainly around the upper cortical surfaces with the inner layer of the periosteum and without periosteum. T1 WI showed no signal around the cortical surfaces, regardless of the periosteum state. The porcine tibia without periosteum showed changes in the high signal area around the cortical surface as the position changed in 3D UTE (FS). No signal was detected around the cortical surface in T1 WI, regardless of the position change. Conclusion: The periosteum showed a high signal in 3D UTE and 3D UTE FS that overlapped with artifacts around the cortical bone.

• 구강회복응용과학지
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• 제23권1호
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• pp.55-68
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• 2007

The purpose of this study was to analyze the distribution of stress in the surrounding bone around implant placed in the first and second molar region. Two different three-dimensional finite element model were designed according to vertical bone level around fixture ($4.0mm{\times}11.5mm$) on the second molar region. A mandibular segment containing two implant-abutments and a two-unit bridge system was molded as a cancellous core surrounded by a 2mm cortical layer. The mesial and distal section planes of the model were not covered by cortical bone and were constrained in all directions at the nodes. Two vertical loads and oblique loads of 200 N were applied at the center of occlusal surface (load A) or at a position of 2mm apart buccally from the center (load B). Von-Mises stresses were analyzed in the supporting bone. The results were as follows; 1. With the vertical load at the center of occlusal surface, the stress pattern on the cortical and cancellous bones around the implant on model 1 and 2 was changed, while the stress pattern on the cancellous bone with oblique load was not. 2. With the vertical load at the center of occlusal surface, the maximum von-Mises stress appeared in the outer distal side of the cortical bone on Model 1 and 2, while the maximum von-Mises stress appeared in the distal and lingual distal side of the cortical bone with oblique load. 3. With the vertical load at a position of 2 mm apart buccally from the center, there was the distribution of stress on the upper portion of the implant-bone interface and the cortical bone except for the cancellous bone, while there was a distribution of stress on the cancellous bones at the apical and lingual sides around the fixture and on the cortical bone with oblique load. 4. With the changes of the supporting bone on the second molar area, the stress pattern on the upper part of the cortical bone between two implants was changed, while the stress pattern on the cancellous bone was not. The results of this study suggest that establishing the optimum occlusal contact considering the direction and position of the load from the standpoint of stress distribution of surrounding bone will be clinically useful.

• The Korean Journal of Physiology
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• 제11권1호
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• pp.45-50
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• 1977

This study was undertaken to investigate the effect of cingulate cortical ablation upon gastric ulceration, and the pathway through which cingulate cortex exerts the effect. 56 female rats were divided equally into cingulate (cingulate cortical ablation), cingulate-vagal (cingulate cortical ablation and vagotomy), normal control and vagal (vagotomy) groups. Cingulate cortex was ablated through a slit-shaped opening (1 mm in width, 13 mm in length) which was made symmetrically on both sides of, and parallel to, the sagittal suture by removing a bone flap from parietal and frontal bones on each side. Vagus nerves on both sides were transected around the distal end of the esophagus. In the normal control animals, surgical intervention ended with scalp incision. All rats were kept without restraint or food deprivation for 3 weeks after surgery. The stomach of each rat was inflated with 7 ml of physiological saline and then removed under deep anesthesia. The mucosal surface was examined under dissecting microscope for the location, shape and number of ulcers, and then enlarged photograph $(4{\times})$was taken. The incidence of ulcer in each group was counted and the number of ulceration as well as the total area of glandular mucosa were measured on the photograph. Results obtained were as follows: 1. The mean number of ulcer per stomach and the total area of ulcer exprssed as permillage of the total area of glandular mucosa were significantly higher in the cingulate group than the cingulate-vagal, the normal control and the vagal groups. There was no difference among the latter three groups. 2. The incidence of ulcer in the cingulate group was significantly higher than that in the .normal control group and was also higher, though not significantly, than those in the cingulate-vagal and the vagal groups. There was no difference among the normal control, the cingulate-vagal and the vagal groups. It is inferred from the above results that the cingulate cortex exerts an inhibitory influence upon gastric ulceration and that this influence is mediated by controlling the vagal activity.

• The Journal of Korean Physical Therapy
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• 제21권1호
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• pp.73-80
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• 2009

Purpose: In order to examine difference in the activity of potential of spinal neurons and cortical neurons according to muscle contraction type in post stroke hemiplegic subjects and healthy subjects, the present study conducted an experiment as follows. Methods: The subjects in the experimental group were 17 left-side hemiplegic subjects (9 female, 8 male; mean age, 63.41$\pm$9.86 years) with the right hand as the dominant hand selected among post stroke hemiplegic subjects, and 17 age matched healthy control subjects (10 female, 7 male; mean age, 64.12$\pm$12.07 years). Movement-related cortical potentials (MRCPs) were measured using surface electromyography and electroencephalography while concentric and eccentric movements were made alternately. Results: As to the pattern of the activity of MRCP, which indicates the activity of motor cortical neurons, we found that the amplitude is high (p<0.01), the length of excitement is short (p<0.01) and the ascending gradient of amplitude to the peak increases (p<0.05) in post stroke hemiplegic subjects' lesion sites different from healthy subjects. Conclusion: The activity of cortical neurons was no difference in activity according to contraction type was observed in post stroke hemiplegic subjects' lesion sites. This suggests that there is no distinction in the activity of cortical neurons between concentric contraction and eccentric contraction. Accordingly, if post stroke hemiplegic subjects' activity of motor cortex is analyzed by measuring MRCPs, it is considered useful in research on neural plasticity or as a ground of clinical effects in the area of physical therapy for the central nervous system.

• 대한치과보철학회지
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• 제36권5호
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• pp.758-771
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• 1998

Assessment of implant mobility is an important and reliable method to clinically evaluate implant stability. PerioTest is a precise and reproducible device that cam dynamically measure the reaction of damping characteristics of peri-implant tissue. The aim of this study is to evaluate the effects of amount of implant surface area, diameter, type, implantation site, degrees of cortical engagement, and length of time in function on PTVs and to find out the most determining factor on PTVs. The results are as follows 1. 5.0mm diameter implants show significantly lower PTV than that of 3.75mm diameter implants. 2. PTV in the mandible is significantly lower than that of the maxilla 3. In the maxilla, there is no significant difference in PTV during the first year of implant function, but during the second year a significant decrease in PTV is noted. 4. In the mandible, there is a significant decrease in PTV during the first and second year of implant function. 5. Implantation site seems to be the most determining factor on PTV among the influencing factors in this study. In conclusion, the amount of implant surface area, type, degrees of cortical engagement had no significant effect on PTV, but installation site and diameter influenced significantly on PTV

• 생물정신의학
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• 제24권2호
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• pp.68-74
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• 2017

Objectives It is well known that problem drinking is associated with alterations of brain structures and functions. Brain functions related to alcohol consumption can be determined by the resting state functional connectivity in various resting state networks (RSNs). This study aims to ascertain the alcohol effect on the structures forming predetermined RSNs by assessing their cortical thickness. Methods Twenty-six abstinent male patients with alcohol dependence and the same number of age-matched healthy control were recruited from an inpatient mental hospital and community. All participants underwent a 3T MRI scan. Averaged cortical thickness of areas constituting 7 RSNs were determined by using FreeSurfer with Yeo atlas derived from cortical parcellation estimated by intrinsic functional connectivity. Results There were significant group differences of mean cortical thicknesses (Cohen's d, corrected p) in ventral attention (1.01, < 0.01), dorsal attention (0.93, 0.01), somatomotor (0.90, 0.01), and visual (0.88, 0.02) networks. We could not find significant group differences in the default mode network. There were also significant group differences of gray matter volumes corrected by head size across the all networks. However, there were no group differences of surface area in each network. Conclusions There are differences in degree and pattern of structural recovery after abstinence across areas forming RSNs. Considering the previous observation that group differences of functional connectivity were significant only in networks related to task-positive networks such as dorsal attention and cognitive control networks, we can explain recovery pattern of cognition and emotion related to the default mode network and the mechanisms for craving and relapse associated with task-positive networks.