뇌과학연구센터 세미나 개최
일시: 2008년 4월 7일(월) 오후 1:00-2:30
장소: KAIST 정문술빌딩 219호
제목: Oscillation and Cortical feedback in Primary Visual Cortex
연사: 강국진 (Research Scientist, RIKEN BSI, Japan)
Visual stimulation enhances the gamma-band (25-90Hz) of the local field potential (LFP) power spectrum in macaque primary visual cortex (V1) and the size and location of the gamma-band peak in the LFP spectrum is correlated with visual stimulus size. We study how cortical recurrent interactions in V1 together with feedback from extrastriate cortex can account for spectral peaks in theV1 LFP. In this talk, I will start with the importance of oscillation in brain and neural circuit theories to explain oscillation and orientation tuning of firing rate in V1. After that, I will explain how cortico-cortical feedback influences the power spectrum of neural networks. We found that the Resonance frequency of our network model is in the gamma band, and shifts with stimulus size, as in the real cortex, because increased size recruits more activity in extrastriate cortex and V1 hereby causing stronger feedback. The model needs to have strong local recurrent inhibition within V1 to obtain ResFs that agree with cortical data.
뇌과학연구센터에서는 다음과 같이 세미나를 개최합니다.
관심있는 분들의 많은 참여 부탁드립니다.
일시 : 2008년 3월 31일(월) 오후 4:00-5:30
장소 : KAIST 정문술빌딩 219호
Title: Independent Vector Analysis for Group Functional MRI Data Processing
Speaker : Jong-Hwan Lee (Research Fellow, Dept. of Radiology, Brigham and Women’s Hospital, Harvard Medical School)
Independent component analysis (ICA) of fMRI data generates session/individual specific brain activation maps without a priori assumptions regarding the timing or pattern of the blood-oxygenation-level-dependent (BOLD) signal responses. However, because of a random permutation among output components, ICA does not offer a straightforward solution for the inference of group-level activation. In this study, we present an independent vector analysis (IVA) method to address the permutation problem during fMRI group data analysis. In comparison to ICA, IVA offers an analysis of additional dependent components, which were assigned for use in the automated grouping of dependent activation patterns across subjects. Our proposed method was applied to real fMRI data employing a single-trial task-paradigm (right hand motor clenching and internal speech generation tasks). A generalized linear model (GLM) and the group ICA of the fMRI toolbox (GIFT) were also applied to the same data set for comparison to IVA. Compared to GLM, IVA successfully captured activation patterns even when the functional areas showed variable hemodynamic responses that deviated from a hypothesized response. We also showed that IVA effectively inferred group-activation patterns of unknown origins without the requirement for a pre-processing stage (such as data concatenation in ICA-based GIFT). IVA can be used as a potential alternative or an adjunct to current ICA-based fMRI group processing methods.
Jong-Hwan Lee received his B.S. degree from Yonsei University, Seoul, in 1998, the M.S. and Ph.D. degrees in Electrical Engineering and Computer Science from the Korea Advanced Institute of Science and Technology (KAIST) in 2000 and 2005, respectively. He was a visiting scholar at the Institute for Neural Computation, University California at San Diego, in 2000. He was a postdoctoral fellow at the Brain Science Research Center (BSRC) and Department of BioSystems at KAIST, in 2005. From 2005, he is a research fellow at the Department of Radiology, Brigham and Women’s Hospital and a research associate at the Harvard Medical School, Boston, MA. His research interests include machine learning algorithms with applications in speech and image data. Recently, he has also worked on biomedical signal analyses such as an automated real-time registration of function MRI (fMRI) data and independent vector analysis (IVA) for group fMRI data processing.
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2008 세계 뇌주간
- 일시: 2008년 3월 15일(토) 오후 1:00-4:30
- 장소: KAIST 정문술빌딩(E16) 드림홀
- 주최: KAIST 뇌과학연구센터 / 바이오및뇌공학과
- 주제 : 뇌와 인지
01:00-01:40 신경과학으로 볼 수 있는 두뇌의 신비 (김대수, KAIST 생명과학과)
01:40-02:20 영화속에서 보는 뇌과학 (정용, KAIST 바이오및뇌공학과)
02:30-03:10 창의적 뇌와 사교적 뇌 (한종혜, 고려대학교 지혜과학센터)
03:10-03:50 마음을 찍는 카메라: 기능성 자기공명영상 (fMRI)
박현욱 (KAIST 뇌과학연구센터/전자전산학과)
04:00-04:30 KAIST 뇌과학연구센터 fMRI 연구실 방문
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