• Korean Journal of Biological Psychiatry
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• v.28 no.2
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• pp.23-35
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• 2021

Fear conditioning and extinction, which are adaptive processes to learn and avoid potential threats, have essential roles in the pathophysiology of anxiety disorders. Experimental fear conditioning and extinction have been used to identify the mechanism of fear and anxiety in humans. However, the brain-based mechanisms of fear conditioning and extinction are yet to be established. In the current review, we summarized the results of neuroimaging studies that examined the brain changes-functional activity and structures-regarding fear conditioning or extinction in healthy individuals. The functional activity of the amygdala, insula, anterior cingulate gyrus, ventromedial prefrontal cortex, and hippocampus changed dynamically with both fear conditioning and extinction. This review may provide an up-to-date summary that may broaden our understanding of pathophysiological mechanisms of anxiety disorder. In addition, the brain regions that are involved in the fear conditioning and extinction may be considered as potential treatment targets in the future studies.

• Proceedings of the Korean Society of Applied Pharmacology
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• 2008.04a
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• pp.33-45
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• 2008

Auditory fear memory is thought to be maintained by fear conditioning-induced potentiation of synaptic efficacy. The conditioning-induced potentiation has been shown to be maintained, at least in part, by enhanced expression of surface AMPA receptor (AMPAR) at excitatory synapses in the lateral amygdala (LA). Depotentiation, reversal of conditioning-induced potentiation, has been proposed as a cellular mechanism for fear extinction. However, a direct link between depotentiation and extinction has not yet been tested. To address this, we applied both ex vivo and in vivo approaches to rats in which fear memory had been consolidated. We found a novel form of ex vivo depotentiation; the depotentiation reversed conditioning-induced potentiation at thalamic input synapses onto the LA (T-LA synapses) ex vivo, and it could be induced only when both NMDA and metabotropic glutamate receptors were co-activated. Extinction returned the enhanced T-LA synaptic efficacy observed in conditioned rats to baseline and occluded the depotentiation. Consistently, extinction reversed conditioning-induced enhancement of surface expression of AMPAR subunits in LA synaptosomal preparations. A GluR2-derived peptide that blocks regulated AMPAR endocytosis inhibited depotentiation, and microinjection of a cell-permeable form of the peptide into the LA attenuated extinction. Our results are consistent with the use of depotentiation to weaken potentiated synaptic inputs onto the LA during extinction, and they provide strong evidence that AMPAR removal at excitatory synapses in the LA underlies extinction. The results described here are in line with previous findings. Neural activity in the LA has been shown to decrease after extinction in the rat and human. The NMDAR dependency of the depotentiation fits nicely with a large body of evidence that fear extinction depends upon amygdala NMDARs. Similarly, blockade of metabotropic glutamate recepotrs in the LA has recently been shown to attenuate fear extinction.

• Molecules and Cells
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• v.37 no.1
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• pp.24-30
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• 2014

Inductive expression of early growth response 1 (Egr-1) in neurons is associated with many forms of neuronal activity. However, only a few Egr-1 target genes are known in the brain. The results of this study demonstrate that Egr-1 knockout (KO) mice display impaired contextual extinction learning and normal fear acquisition relative to wild-type (WT) control animals. Genome-wide microarray experiments revealed 368 differentially expressed genes in the hippocampus of Egr-1 WT exposed to different phases of a fear conditioning paradigm compared to gene expression profiles in the hippocampus of KO mice. Some of genes, such as serotonin receptor 2C (Htr2c), neuropeptide B (Npb), neuronal PAS domain protein 4 (Npas4), NPY receptor Y1 (Npy1r), fatty acid binding protein 7 (Fabp7), and neuropeptide Y (Npy) are known to regulate processing of fearful memories, and promoter analyses demonstrated that several of these genes contained Egr-1 binding sites. This study provides a useful list of potential Egr-1 target genes which may be regulated during fear memory processing.

• Korean Journal of Biological Psychiatry
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• v.18 no.2
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• pp.80-89
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• 2011

Pavlovian fear conditioning has been extensively studied for the understanding of neurobiological basis of memory and emotion. Pavlovian fear conditioning is an associative memory which forms when conditioned stimulus (CS) is paired with unconditioned stimulus (US) once or repeatedly. This behavioral model is also important for the understanding of anxiety disorders such as posttraumatic stress disorder. Here we describe the neural circuitry involved in fear conditioning and the molecular mechanisms underlying fear memory formation. During consolidation some memories fade out but other memories become stable and concrete. Emotion plays an important role in determining which memories will survive. Memory becomes unstable and editable again immediately after retrieval. It opens the possibility for us of modulating the established fear memory. It provides us with very efficient tools to improve the efficacy of cognitive-behavior therapy and other exposure-based therapy treating anxiety disorders.

• Anxiety and mood
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• v.6 no.2
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• pp.102-108
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• 2010

Objective : Although studies have explored responses to fear had been assessed using various psychophysiological methods, results have been inconsistent. The present study examined psychophysiological responses in healthy subjects after viewing fear stimuli in a video clip for set up future fear related psychophysiological studies. Methods : We monitored three psychophysiological variables (electroencephalography, skin temperature, and heart rate variability) in adults who watched either a control stimulus movie clip or a fear-inducing movie clip. Results : In 16 healthy adults, theta activity decreased significantly after the fear stimulus as compared to the normal stimulus. However the participants showed no differences in heart rate variability or skin temperature between the fear and normal control stimulus situations. Conclusion : In the limbic area, theta activity corresponds with information processing, integration into previous memories and long-term potentiation. In this study, we suggest decreased theta activity represents amygdalo-hippocampal activity, associated with fear, short-term memory, and memory extinction in the healthy adults. Further studies are needed to evaluate the interaction of fear, memory, and the pathophysiology of anxiety disorder in patient with anxiety disorders.

• Korean Journal of Hospice Care
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• v.8 no.1
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• pp.1-12
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• 2008

Perpose: The purpose of this study was to investigate the perception of death between Korean and Chinese nursing students. And it will help develop curriculum for preparing death, the quality of hospice care, as well as nursing education and practice. Methods: Data was collected from 492 nursing students participated(248 Korean and 244 Chinese) by questionnaire designed for examining Death Orientation (Thorson & Powell, 1988). They were analyzed using Cronbach's Alpha coefficients, factor analysis, t-test, ANOVA and regression analysis (SPSS; win 12.0 version) Results: More than half of the Korean nursing students followed a religion (58.5%) while the majority of Chinese nursing students did not follow a religion (93.9%). In the view of the afterlife, nursing students in China had two views. 'I really don't know what happens after a person dies (30.3%)' and ‘There is no afterlife and death is the end (29.5%)’. On the other hand the Korean nursing students’ answer were, 'After dying, a person goes to heaven or hell (27.3%)' and 'I really don't know what happens after a person dies. (22.9%)' The study also found that the average of 25 items in Death Orientation is 2.36points of nursing students in Korea and 2.50points of nursing students in China. This means that the concern, anxiety and fear were of the middle level for the Chinese Students and were higher than Korean students (t=3.51, p=.000). In the low factor of death orientation, those in Korea had higher 'anxiety of burden to family' than those in China (t=-3.50, p=.001). The nursing students in China had higher 'anxiety of the unknown (t=4.96, p=.000)', 'fear of suffering (t=6.88, p=.000), 'fear of extinction body and life (t=5.20, p=.000), 'fear of lost self-control(t=2.12, p=.034)', and 'anxiety of future existence and nonexistence (t=2.33, p=.020)' than those in Korea. There was no statistically significant difference for the 'concern of body and fear of identity lost' category. The death orientation of Korean nursing students had statistically significant differences according to age (t=3.20, p=.002), religion (t=2.56, p=.011), and afterlife (F=4.64, p=.000). The contribution of Death Orientation had a statistically significant difference, the afterlife variable (0.735, p=0.001). The death orientation of Chinese nursing students did not have any statistically significant differences. Conclusion: In conclusion, there were differences in death orientation between Korean and Chinese nursing students. In particular, those who believed in afterlife showed acceptance of death. The results of this study suggest that nursing curricula should include education program on death and spiritual nursing. Additional studies are needed to establish death education in China with careful considerations on Chinese policies, cultures and social systems.

• Journal of the Korean Society of Costume
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• v.54 no.3
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• pp.145-158
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• 2004

In modern art, body appears as artistic performer, material or producer. and is expressed as' social environment body' which is changed in the relationship with its society and culture. The correlation between body and clothing image appears in 'body as expression object' which directly borrows human body or sets up a section of human body, 'body as medium' in which clothing substitutes body, and 'body as image' in which image of body reappears along with clothing. The results of analysis are as follows : First, 'image of expansion and exaggeration' to expand the influence of clothing thereby disclosing illusion of material civilization prevalent in our society, and make metaphor of dwarfish human's lurking fear by transforming and exaggerating human body. Second, 'image of restriction and suppression' to express the loss of humanity, power and restriction of modern society with fixing and cruelty of body image through clothing which disregard body function. Third, 'image of open and fluidity to criticize the extinction of values of human existence and standardized figure of our society by reducing three-dimensional clothing and body to untypical form or introducing the image of absent of human body to clothing. Fourth, 'image of reversion and paradox' to express practical clothing object with unwearable material, or cause confusion of sex and identity by expressing dual aspects of body at the same time. In this study, which is focused on correlation between body and clothing and the meaning of them, I realized that, even though artistic clothing expressed image of distortion and deformation of human existence as essential subject of body, they, in most contents, were used as medium of communication to rediscover human dignity and identity, and consisted of a series of metaphoric network of meanings satirizing aspects of our society.