Prof. Yoonkey Nam received a three-year research grant with Prof. Ruedi Stoop (link) at the Institute of Neuroinformatics of University and ETH Zurich. The proposal titled ‘CHIP: Cross-scale High-res Investigation of Power-laws in neural networks’ were submitted through the Korea-Swiss Science and Technology Programe (link) sponsored by Korea and Swiss government. Prof Nam and Prof Stoop will investigate the dynamics and topology of neural networks at the micro- and macro-scales and the access their relationship to functions. Through their research, they expect to establish a paradigm shift in data-driven science in neural circuits and develop a innovative multidimensional neural data processing technique for neural prostheses and neural circuit disorders.
Prof. Andreas Hierlemann (ETH Zurich, link), who is one of the world leading researchers in MEA technology, visited us while he was attending MicroTAS 2015 in Korea. He spend one day with NEL students sharing his recent results on CMOS MEA system.
Effects of ECM protein micropatterns on the migration and differentiation of adult neural stem cells
Sunghoon Joo, Joo Yeon Kim, Eunsoo Lee, Nari Hong, Woong Sun & Yoonkey Nam This is an outcome of our on-going collaboration with Prof. Woong Sun's lab in Korea University (고려대학교 해부학 교실, 선웅 교수). In this work, Sunghoon (KAIST, NEL) and Joo Yeon (Korea University College of Medicine) applied soft-lithographic technique to design simple and reproducible laminin (LN)-polylysine cell culture substrates and investigated how aNSCs respond to the various spatial distribution of laminin, one of ECM proteins enriched in the aNSC niche. They found that aNSC preferred to migrate and attach to LN stripes, and aNSC-derived neurons and astrocytes showed significant difference in motility towards LN stripes. By changing the spacing of LN stripes, they discovered a new way of separating neurons and astrocytes differentiated from adult neural stem cells. To the best of our knowledge, this is the first time to investigate the differential cellular responses of aNSCs on ECM protein (LN) and cell adhesive synthetic polymer (PDL) using surface micropatterns. NeuroCa: Integrated framework for systematic analysis of spatio-temporal neuronal activity patterns from large-scale optical recording data
Minjee Jang and Yoonkey Nam In this work, Minjee developed a MATLAB-based toolbox, named NeuroCa, for the automated processing and quantitative analysis of large-scale calcium imaging data. This tool includes several computational algorithms to extract the calcium spike trains of individual neurons from the calcium imaging data in an automatic fashion. Two algorithms were developed to decompose the imaging data into the activity of individual cells and subsequently detect calcium spikes from each neuronal signal. Applying our method to dense networks in dissociated cultures, we were able to obtain the calcium spike trains of ∼1000 neurons in a few minutes. Further analyses using these data permitted the quantification of neuronal responses to chemical stimuli as well as functional mapping of spatiotemporal patterns in neuronal firing within the spontaneous, synchronous activity of a large network. These results demonstrate that our method not only automates time-consuming, labor-intensive tasks in the analysis of neural data obtained using optical recording techniques but also provides a systematic way to visualize and quantify the collective dynamics of a network in terms of its cellular elements. For more information please go to the NeuroCa webpage (link)
Gated Luminescence Imaging of Silicon Nanoparticles
Jinmyoung Joo , Xiangyou Liu , Venkata Ramana Kotamraju , Erkki Ruoslahti , Yoonkey Nam , and Michael J. Sailor In this work, Prof. Nam developed imaging instrumentation and data analysis method while he was staying in Dr. Sailor's group for his sabbatical. He lead the project for 6 month and the project was taken over by Dr. Joo who successfully applied it to tumor tissues. This work uses time-resolved photoluminescence imaging technique to locate drug-loaded porous silicon nanoparticles that has extremely long life-time compared to conventional fluorescence probe molecules. This is the first technical paper on the instrumentation of time-gated life-time imaging of porous silicon nanoparticles using an intensified CCD camera and pulsed LED light sources. (Link) Minjee Jang's work on agarose-assisted microstamping method was selected as the cover article. Dae-Jeong Kim helped to design the cover image. Agarose-assisted micro-contact printing uses a stamp covered with agarose thin film, enabling the effective patterning of biomolecules to guide neuronal growth on the substrate. Various patterns including dots with a few micrometers in diameter are also available to be patterned using the method presented by M. J. Jang and Y. Nam on page 613. (Cover designed by M. J. Jang and D. J. Kim.) Source: Jang et al., Macro. Bioscience 2015 (link)
Emerging Neural Stimulation Technologies for Bladder Dysfunctions
Jee Woong Lee, Daejeong, Kim, Sangjin Yoo, Hyungsup Lee, Gu-Haeng Lee, Yoonkey Nam This review article introduced state-of-the-art neural stimulation technologies including microelectrode array technology, closed-loop stimulation, infrared neural stimulation, optogenetics, and ultrasound stimulation. Authors were invited to write an article to review new technological breakthroughs that could be potentially applicable to bladder control problems in clinic. This article appeared in International Neurourology Journal in March, 2015. (link) Electrochemical layer-by-layer approach to fabricate mechanically stable platinum black microelectrodes using a mussel-inspired polydopamine adhesive
Raeyoung Kim and Yoonkey Nam In this work, we applied a mussel-inspired polydopamine chemistry to fabricate mechanically stable neural microelectrodes (platinum black electrodes). The main motivation was to show that polydopamine can serve as a molecular adhesive layer to stablize platinum black nanostructures on gold film. Using our previously developed electrochemical deposition of polydopamine layers, we successfully developed a platinum black hybrid micro-structures that had superior mechanical properties. (Link) In vitro neurite guidance effects induced by polylysine pin-stripe micropatterns with polylysine background
Sung Hoon Joo, Kyungtae Kang, Yoonkey Nam This work showed that neurite guidance effect can be induced only using synthetic biopolymer (poly-lysine). The pin-stripe micropattern was fabricated by stamping poly-L-lysine (PLL) on a PLL coated glass coverslip, which resulted denser PLL lines and less dense PLL background. There were two effects of the substrate on cultured primary hippocampal neuron: neurite initiation and growth cone turning. Although the whole surface was permissive for neurite outgrowth, we observed that the growth direction of neurites had a strong tendency to follow the stamped PLL line patterns with PLL background. (article link) BRIC 한빛사에 주성훈 학생의 최근 PNAS 논문 인터뷰가 실렸습니다. 인터뷰 링크
Sunghoon interviewed with BRIC concerning his work published in PNAS . Tissue-based metabolic labeling of polysialic acids in living primary hippocampal neurons.
Kang Kyung Tae, Joo Sung Hoon, Choi JY, Geum S, Hong S, Lee S, Kim YH, Kim S, Yoon M, Nam Y*, Lee K*, Lee H (link)*, Choi IS (link)* In this work, we developed a tissue-based strategy for metabolic incorporation of a chemical reporter to primary neurons. We let an unnatural monosaccharide be metabolized by hippocampal tissues before dissociation into individual cells, and thereby, we could eliminate cytotoxicity. We used this method to describe, for the first time to our knowledge, the real-time distribution of polysialic acids on the membranes of neurons. Current member Sung Hoon Joo, previous member Dr. Kyungtae Kang, and JY Choi from Choi lab (link) did a great collaboration to make this happen. Article abstract (Link) Agarose-Assisted Micro-Contact Printing for High-Quality Biomolecular Micro-Patterns
Min Jee Jang, Yoonkey Nam This work reports a novel surface modification of a PDMS stamp for micro-contact printing of biomolecules. We developed a method to form a thin agarose-hydrogel layer on a PDMS stamp, which greatly enhanced the quality of printed micropatterns in terms of uniformity and ink transfer. This is the second paper on a micro-contact printing from NEL. (Link) 한국연구재단 우수논문상 수상
남윤기 교수의 최신 신경세포칩 기술 동향을 다룬 논문이 한국연구재단 기초연구본부 전자정보 융합연구단에서 선정하는 우수논문상(융합분야)을 수상하였습니다. Professor Nam's recent review article that he coauthored with NEL members was selected as one of the best papers from National Research Foundation.
MicroTAS was held at San Antonio, Texas. Sung-hoon Joo presented a poster on agrose hydrogel patterning for constructing neuronal networks on microelectrode arrays. His poster was ranked top 20 % among all posters.
Prof. Luke Lee (UC Berkeley, link), who is one of the world leading researchers in nanobiotechnology, visited us while he was attending a conference near KAIST. He spend a few hours with NEL students discussing about the important role of technology in neurobiology.
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