• Journal of Korean Neurosurgical Society
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• v.29 no.1
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• pp.5-14
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• 2000

Objective : Somatosensory evoked potential(SSEP) has been known to be a good method for evaluating brain stem function, but it is not sufficient to check the fine changes of cortical functions. A fine change of cortical function can be expressed with somatosensory evoked cortical field potential(SSEFP) rather than general SSEP. To confirm the usefulness of SSEFP for evaluating the cortical function, the authors simultaneously measured SSEFP and the intracranial pressure-volume index(PVI) in kaolin-induced hydrocephalic rats. Method : Hydrocephalus was induced with injection of 0.1ml kaolin-suspended solution into the cisterna magna in 60 Sprague-Dawley rats. The authors measured PVI and SSEFP 1 week after injection of kaolin-suspended solution. To evaluate the severity of induced hydrocephalus, we measured the transverse diameter of the lateral ventricle on the coronal slice of the rat brain 0.40mm posterior to the bregma. Result : The typical wave form of SSEFP in control rats showed a negative-positive complex wave at early latency. In SSEFP of normal rats, N0 is 10.0 msec, N1 15.3 msec, P1 31.2 msec and N1-P1 amplitude $15.4{\mu}V$. As hydrocephalus progressed, the peak latency of N1 and P1 were delayed. In mild hydrocephalus, negative peak waves were split. The N1-P1 amplitude was decreased only in severe hydrocephalus. The changes of the characteristics of SSEFP according to the severity of hydrocephalus were well correlated with the changes of PVI. Shunting normalized the characteristics of SSEFP in relation to ventricular sizes and PVI in hydrocephalic rats. Conclusion : SSEFP may be useful for evaluating the impairment of cortical function in hydrocephalus.

• Journal of Physiology & Pathology in Korean Medicine
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• v.23 no.3
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• pp.645-661
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• 2009

The water extract of Dohongsamul-Tang(DHSMT) has been traditionally used to stroke and brain injuries in Oriental Medicine. The present study was designed to investigate the effects of DHSMT on the gene expression profile of cerebral infarction by cDNA microarray in photothrombotic ischemia mouse model. Photothrombotic ischemia was induced in stereotactically held male BALB/c mice using rose bengal and cold light. MRI was performed 24 hours after inducing photothrombosis using 1.5 T MRI and 47 mm surface coil to obtain T2-weighted, and contrast-enhanced images. After MRI test, animal was sacrificed and the brain sections were stained for hematoxylin and eosin and immunohistochemistry. MRI and histological analysis revealed that lesion of thrombotic ischemia was well induced in the cortex with the evidence of biological courses of infarction. The target area of thrombotic infarction was 1 mm anterior to bregma and 3 mm lateral to midline with 2 mm in diameter, which were decreased by administration of DHSMT. To assess gene expression pattern of cerebral infarction, mRNA was isolated and reacted with microarray chip(Agilant's DNA Microarray 44K). Scatter and MA plot analysis were performed to clustering of each functional genes. M value [M=log2(R/G), A={log2(R ${\times}$ G)}/2] was between -0.5 and +0.5 with 40% difference. After pretreatment with DHSMT, the expression levels of mRNA of many genes involved in various signaling pathway such as apoptosis, cell cycle, cell proliferation, response to oxidative stress, immune response, angiogenesis, and inflammatory cytokine were markedly inhibited in photothrombotic ischemia lesion compared to the control group. These results suggest that DHSMT prevent ischemic death of brain on photothrombotic ischemia model of mice through modulation of gene expression at the transcriptional level.

• The Journal of Korean Medicine
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• v.20 no.3 s.39
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• pp.36-44
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• 1999

Objectives: It has been well known that electroacupuncture(EA) has an analgesic effect and there is a pain control system in the central nervous system(CNS). The pain control system is composed of three major nuclei, which are periaqueductal gray(PAG), raphe nuclei, and the pain inhibitory complex located in the spinal cord. It has been suggested that the analgesic effect of EA might be the result of activation of the pain control system in the CNS. However, there may be a possibility that other nuclei are also involved in this pain modulation. Thus, we investigated whether the posterior intralaminar thalamic nuclei (PTIN) are involved in the pain modulation. Methods: To measure the level of pain, the jaw opening reflex (JOR) was used as a pain index. The magnitude of JOR is estimated by averaging the area of 10 successive responses. JOR was evoked by tooth-pulp stimulation with bipolar electrode carrying stimulus with the following parameters: intensity ranging from 420uA to 680ulA, 0.3ms duration of square pulse, and 0.5 Hz. Hapkog($LI_4$) and Taechung ($LR_3$) were the chosen acupoints. The Hapkog point was stimulated ipsilaterally at 5V, 3 Hz, for 15min in total, and the Taechung was stimulated at 2-3 V, 3 Hz, and for a total of 15 or 30 minutes. Different intensities of stimulation were given the PITN; one was given at $300{\mu}A$ and the other was at 500uA. The position stimulated in these nuclei by Paxinos Atlas was AP; from bregma $-4.0{\sim}-4.3mm,\;L; 0.5{\sim}1.8mm,\;D;\;4.8{\sim}6.3mm$. Results: The Hapkog point had a significant analgesic effect (P<0.05). However, the Taechung point had no effect. Both types of stimulation in the PITN did not reveal any analgesic effects. Conclusions: From these results, it was suggested that the posterior intralaminar thalamic nuclei are not involved in the modulation of pain.

• Journal of Korean Neurosurgical Society
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• v.30 no.7
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• pp.831-841
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• 2001

Objective : Somatosensory evoked potentials(SSEPs) have been used widely both experimentally and clinically to monitor the function of central nervous system and peripheral nervous system. Studies of SSEPs have reported the various recording techniques and patterns of SSEP. The previous SSEP studies used scalp recording electrodes, showed mean vector potentials which included relatively constant brainstem potentials(far-field potentials) and unstable thalamocortical pathway potentials(near-field potentials). Even in invasive SSEP recording methods, thalamocortical potentials were variable according to the kinds, depths, and distance of two electrodes. So they were regarded improper method for monitoring of upper level of brainstem. The present study was conducted to investigate the characteristics of somatosensory evoked field potentials(SSEFPs) of the cerebral cortex that evoked by hindlimb stimulation using ball electrode and the pathways of SSEFP by recording the potentials simultaneously in the cortex, VPL nucleus of thalamus, and nucleus gracilis. Methods : In the first experiment, a specially designed recording electrode was inserted into the cerebral cortex perpendicular to the cortical surface in order to recording the constant cortical field potentials and SSEFPs mapped from different areas of somatosensory cortex were analyzed. In the second experiment, SSEPs were recorded in the ipsilateral nucleus gracilis, the contralateral ventroposterolateral thalamic nucleus(VPL), and the cerebral cortex along the conduction pathway of somatosensory information. Results : In the first experiment, we could constantly obtain the SSEFPs in cerebral cortex following the transcutaneous electrical stimulation of the hind limb, and it revealed that the first large positive and following negative waves were largest at the 2mm posterior and 2mm lateral to the bregma in the contralateral somatosensory cortex. The second experiment showed that the SSEPs were conducted by way of posterior column somatosensory pathway and thalamocortical pathway and that specific patterns of the SSEPs were recorded from the nucleus gracilis, VPL, and cerebral cortex. Conclusion : The specially designed recording electrode was found to be very useful in recording the localized SSEFPs and the transcutaneous electrical stimulation using ball electrode was effective in evoking SSEPs. The characteristic shapes, latencies, and conduction velocities of each potentials are expected to be used the fundamental data for the future study of brain functions, including the hydrocephalus model, middle cerebral artery ischemia model, and so forth.

• The Korean Journal of Nuclear Medicine
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• v.38 no.6
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• pp.528-531
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• 2004

Purpose: PET has some disadvantage in the imaging of small animal due to poor resolution. With the advent of microPET scanner, it is possible to image small animals. However, the image quality was not good enough as human image. Due to larger brain, cat brain imaging was superior to mouse or rat. In this study, we established the cat brain infarction model and evaluate it and its temporal charge using microPET scanner. Materials and Methods: Two adult male cats were used. Anesthesia was done with xylazine and ketamine HCl. A burr hole was made at 1cm right lateral to the bregma. Collagenase type IV 10 ${\mu}l$ was injected using 30 G needle for 5 minutes to establish the infarction model. $^{18}F$-FDG microPET (Concorde Microsystems Inc., Knoxville, TN) scans were performed 1, 11 and 32 days after the infarction. In addition, $^{18}F$-FDG PET scans were performed using human PET scanner (Gemini, Philips medical systems, CA, USA) 13 and 47 days after the infarction. Results: Two cat brain infarction models were established. The glucose metabolism of an infarction lesion improved with time. An infarction lesion was also distinguishable in the human PET scan. Conclusion: We successfully established the cat brain infarction model and evaluated the infarcted lesion and its temporal change using $^{18}F$-FDG microPET scanner.