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GluA1 phosphorylation at serine 831 in the lateral amygdala is required for fear renewal
Lee, Sukwon,Song, Beomjong,Kim, Jeongyeon,Park, Kyungjoon,Hong, Ingie,An, Bobae,Song, Sangho,Lee, Jiwon,Park, Sungmo,Kim, Jihye,Park, Dongeun,Lee, C Justin,Kim, Kyungjin,Shin, Ki Soon,Tsien, Richard W Nature Publishing Group, a division of Macmillan P 2013 NATURE NEUROSCIENCE Vol.16 No.10
Fear renewal, a widely pursued model of post-traumatic stress disorder and phobias, refers to the context-specific relapse of conditioned fear after extinction. However, its molecular mechanisms are largely unknown. We found that renewal-inducing stimuli, generally believed to be insufficient to induce synaptic plasticity, enhanced excitatory synaptic strength, activity of synaptic GluA2-lacking AMPA receptors and Ser831 phosphorylation of synaptic surface GluA1 in the lateral nucleus of the amygdala (LAn) of fear-extinguished rats. Consistently, the induction threshold for LAn synaptic potentiation was considerably lowered after extinction, and renewal occluded this low-threshold potentiation. The low-threshold potentiation (a potential cellular substrate for renewal), but not long-term potentiation, was attenuated by dialysis into LAn neurons of a GluA1-derived peptide that competes with Ser831-phosphorylated GluA1. Microinjections of the same peptide into the LAn attenuated fear renewal, but not fear learning. Our findings suggest that GluA1 phosphorylation constitutes a promising target for clinical treatment of aberrant fear-related disorders.
Liquid‐metal‐fluidically polarization reconfigurable microstrip patch antenna
Lee, Minjae,Son, Hyunwoo,Lim, Daecheon,Lee, Sukwon,Lim, Sungjoon John Wiley Sons, Inc. 2019 MICROWAVE AND OPTICAL TECHNOLOGY LETTERS Vol.61 No.10
<P><B>Abstract</B></P><P>In this article, we propose a liquid‐metal‐fluidically polarization reconfigurable microstrip patch antenna. The edge‐truncated patch is designed to generate circular polarization (CP), and two microfluidic channels are designed for the polarization reconfigurability. Therefore, the polarization of the proposed antenna is switched to linear polarization (LP) from the CP when the liquid metal is injected on the microfluidic channels. The microfluidic channels are fabricated on the polydimethylsiloxane (PDMS) material, and eutectic gallium‐indium (EGaIn) is used as the liquid metal. The performance of the proposed antenna is numerically and experimentally demonstrated. The measured 10‐dB impedance bandwidth is 1.579‐1.619 GHz and 1.563‐1.587 GHz for the CP and LP modes, respectively. At the CP mode, the measured axial ratio (AR) and RHCP gain at 1.595 GHz are 2.267 dB and 6.59 dBic, respectively. At the LP mode, the measured AR and peak gain at 1.585 GHz are 12.335 dB and 5.18 dBi, respectively.</P>
Lee, Cheol Gyu,Kang, Seungyoon,Oh, Jinyoung,Eom, Min Sik,Oh, Jusung,Kim, Min-Gon,Lee, Woon Seob,Hong, Sukwon,Han, Min Su Elsevier 2017 Tetrahedron letters: the international organ for t Vol.58 No.46
<P><B>Abstract</B></P> <P>In this study, a colorimetric and fluorescent chemosensor for mercury ions (Hg<SUP>2+</SUP>) was developed. Cationic polydiacetylene (PDA) vesicles with a quaternary ammonium cation and iodide as a counterion show a blue-to-red color transition; the color change is accompanied by a fluorescence enhancement in selective response to Hg<SUP>2+</SUP> ions because of a perturbation of the ene–yne conjugated backbone induced by counterion exchange. It allows for selective detection of Hg<SUP>2+</SUP> with the naked eye and the sensor is used to determine Hg<SUP>2+</SUP> concentrations in tap water samples.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A chemosensor for Hg<SUP>2+</SUP> was developed using counterion exchange of cationic PDA. </LI> <LI> It shows colorimetric and fluorescence response toward Hg<SUP>2+</SUP> and allows naked-eye detection. </LI> <LI> It is applied to determine Hg<SUP>2+</SUP> concentrations in tap water samples. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Endogenous amyloid-β mediates memory forgetting in the normal brain
Lee, Sukwon,Kim, Jeongyeon,Choi, Sukwoo Elsevier 2018 Biochemical and biophysical research communication Vol.506 No.3
<P><B>Abstract</B></P> <P>Amyloid beta (Aβ) is known to be one of the strong candidate molecules for initiating Alzheimer's disease and has been extensively studied in the light of disease pathophysiology. However, it is still elusive what roles Aβ play in the normal brain. In this study, we report that Aβ is required for memory forgetting in the normal brain. We monitored object recognition memory, and in order to quench soluble Aβ, we microinjected anti-Aβ antibody (4G8) into the ventricles after memory acquisition. Microinjection of anti-Aβ antibody prolonged the maintenance of object recognition memory. This effect appeared not to be due to modulation of memory consolidation since antibody injection after memory consolidation still had a similar effect on memory maintenance. Furthermore, the maintenance of object recognition memory was prolonged in <I>Fcgr2b</I> KO mice, which lacks IgG Fcγ receptor II-b (FcγRIIb), a receptor for soluble Aβ oligomers. Taken together, these findings suggest that endogenous Aβ is involved in memory forgetting in the normal brain.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Injection of anti-Aβ antibody into the ventricles prolonged object recognition memory. </LI> <LI> It was also effective when injected after memory consolidation. </LI> <LI> Genetic deletion of FcγRIIb, an Aβ receptor, prolonged object recognition memory. </LI> </UL> </P>
Projective Motion Correction with Contact Optimization
Lee, Sukwon,Lee, Sung-Hee IEEE Computer Society 2019 IEEE transactions on visualization and computer gr Vol.25 No.4
<P>When motion capture data is applied to virtual characters, the applied motion often exhibits geometric and physical errors, which necessitates a cumbersome refinement process. We present a novel framework to efficiently obtain a corrected motion as well as its supporting contact information from multi-contact motion capture data. To this end, first, we present a projective dynamics-based method for optimizing character motions. By carefully defining objective functions and constraints using differential representation of motions, we develop a highly efficient motion optimizer that can create geometrically and dynamically adjusted motions given reference motion data and contact information. Second, we develop a contact optimizer that finds a set of contacts that allows the motion optimizer to generate a motion that best follows the reference motion under dynamic and geometric constraints. This is achieved by iteratively improving the hypothesis on the best set of contacts by getting feedback from the motion optimizer. We demonstrate that our method significantly improves the naturalness of a wide range of motion capture data, from walking to rolling.</P>
Lee, Eun Jeong,Son, Gi Hoon,Chung, Sooyoung,Lee, Sukwon,Kim, Jeongyeon,Choi, Sukwoo,Kim, Kyungjin The Society 2011 The Journal of neuroscience Vol.31 No.19
<P>The environment in early life elicits profound effects on fetal brain development that can extend into adulthood. However, the long-lasting impact of maternal stress on emotional learning remains largely unknown. Here, we focus on amygdala-related learning processes in maternally stressed mice. In these mice, fear memory consolidation and certain related signaling cascades were significantly impaired, though innate fear, fear memory acquisition, and synaptic NMDA receptor expression in the amygdala were unaltered. In accordance with these findings, maintenance of long-term potentiation (LTP) at amygdala synapses, but not its induction, was significantly impaired in the maternally stressed animals. Interestingly, amygdala glucocorticoid receptor expression was reduced in the maternally stressed mice, and administration of glucocorticoids (GCs) immediately after fear conditioning and LTP induction restored memory consolidation and LTP maintenance, respectively, suggesting that a weakening of GC signaling was responsible for the observed impairment. Furthermore, microinfusion of a membrane-impermeable form of GC (BSA-conjugated GC) into the amygdala mimicked the restorative effects of GC, indicating that a nongenomic activity of GC mediates the restorative effect. Together, these findings suggest that prenatal stress induces long-term dysregulation of nongenomic GC action in the amygdala of adult offspring, resulting in the impairment of fear memory consolidation. Since modulation of amygdala activity is known to alter the consolidation of emotionally influenced memories allocated in other brain regions, the nongenomic action of GC on the amygdala shown herein may also participate in the amygdala-dependent modulation of memory consolidation.</P>