Sakai Ko

J-GLOBAL         Last updated: Nov 7, 2019 at 02:41
 
Avatar
Name
Sakai Ko
E-mail
sakaics.tsukuba.ac.jp
URL
http://www.cvs.cs.tsukuba.ac.jp/~ko/welcome.html
Affiliation
University of Tsukuba
Section
Faculty of Engineering, Information and Systems
Job title
Professor
Degree
Ph.D. in Bioengineering(University of Pennsylvania), Master in Bioengineering(University of Pennsylvania)

Research Areas

 
 

Academic & Professional Experience

 
1995
 - 
1997
フロンティア研究システム
 
1997
 - 
Nov 1999
Scientist, RIKEN Brain Science Institute
 
Dec 1999
 - 
Mar 2009
Associate Professor, University of Tsukuba
 
Apr 2009
   
 
Professor, University of Tsukuba
 

Education

 
 
 - 
Mar 1983
Faculty of Electro Communications, The University of Electro-Communications
 
 
 - 
Mar 1985
Graduate School, Division of Electro Communications, The University of Electro-Communications
 
 
 - 
May 1995
Bioengineering, Graduate School, Division of Science and Engineering, University of Pennsylvania
 

Committee Memberships

 
Jan 2014
 - 
Nov 2014
International Conference on Neural Information Processing, 2014  Program Committee/member
 
Jan 2014
 - 
Jul 2014
International Joint Conference on Neural Networks  Program Committee/member
 
Jan 2014
 - 
Nov 2016
International Conference on Pattern Recognition  Program Committee/member
 
2011
   
 
Editorial Board, member
 
2010
 - 
2014
科学研究費委員会審査委員
 
Sep 2003
 - 
Jul 2006
Board member
 
2002
 - 
2006
Fellowship Committee, member
 
2005
 - 
2005
Optics Japan 2005
 
2004
 - 
2004
HFSP 15th Anniversary - Annual Meeting
 

Awards & Honors

 
Nov 2013
ICONIP 2013, Cognitive Science Paper Award, Cognitive Science Society
Winner: K. Sakai & S. Michii
 

Published Papers

 
サルV4図地選好性細胞の受容野構造
木村, 耕治;山根, ゆか子;田村, 弘;酒井, 宏
電子情報通信学会技術報告   118(470) 181-185   Mar 2019
Sakata, Yu;Kurematsu, Ken;Wagatsuma, Nobuhiko;Sakai, Ko
JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION   36(2) 283-291   Feb 2019   [Refereed]
Wagatsuma, Nobuhiko;Urabe, Mika;Sakai, Ko
Frontiers in psychology   9    Sep 2018   [Refereed]
Analysis of real-world illumination -Lighting changes perception of specularity-
Mori, Yuito;Sakai, Ko
Journal of Science and Technology in Lighting   42 in press   2018   [Refereed]
Hasuike, M.;Yamane, Y.;Tamura, H.;Sakai, K.
Lecture Note in Computer Science, Springer   9947 131-137   Oct 2016   [Refereed]
Figure-ground (FG) segregation is a crucial function of the intermediate-level vision. Physiological studies on monkey V2 have reported border-ownership (BO) selective cells that signal the direction of figure along a local border. However, local ...
Kudou, K.;Sakai, K.
Lecture Note in Computer Science, Springer   9950 208-212   Oct 2016   [Refereed]
Perception of the material quality of a surface depends on its reflectance properties. Recent physiological studies reported the neural selectivity to glossy surfaces in the Inferior Temporal cortical areas [e.g., 1]. In the present study, we exam...
Hatori,Yasuhiro;Sakai,Ko
JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION   33(4) 527-537   Apr 2016   [Refereed]
Sakai,Ko;Matsuoka,Shouhei;Kurematsu,Ken;Hatori,Yasuhiro
FRONTIERS IN PSYCHOLOGY   6 1685   Nov 2015   [Refereed]
Hasuike,Masaharu;Ueno,Shuto;Minowa,Dai;Yamane,Yukako;Tamura,Hiroshi;Sakai,Ko
Lecture Notes in Computer Science   9490 617-622   Nov 2015   [Refereed]
Sakai,Ko;Meiji,Ryoko;Abe,Tetsuya
VISION RESEARCH   115(B::SI) 188-198   Oct 2015   [Refereed]
We investigated whether specular highlights facilitate the perception of shape from shading in a search paradigm and how highlights interact with shading to facilitate this perception. Our results indicated that stimuli containing highlights led t...
視覚皮質の相互作用が決定するBorder-Ownership細胞のダイナミクス.
Nobuhiko,Wagatsuma;Sakai,Ko
日本神経回路学会,全国大会,講演論文集   38-39   Sep 2015   [Refereed]
Qiu,Wei;Hatori,Yasuhiro;Sakai,Ko
NEUROCOMPUTING   149(B) 546-558   Feb 2015   [Refereed]
The perceptual constancy of shape, including view invariance, is an amazing property of the visual system. Cortical representation by the medial axis (MA) is an attractive candidate for maintaining the constancy of a wide range of arbitrary shapes...
A search for material representation in the cortex
Sakai,Ko
The Proceedings of Annual Conference of Japanese Neural Network Society   1(1) 42-43   Sep 2014   [Refereed]
Hatori,Yasuhiro;Sakai,Ko
Journal of Optical Society of America, A   31(4) 716-729   Apr 2014   [Refereed]
Construction of surface is a crucial step toward the representation of shape through the integration of local information. Physiological studies have reported that the primary visual cortex (V1) codes the medial axis ( MA) that is a skeletal struc...
Wagatsuma,Nobuhiko;Potjans,Tobias C.;Diesmann,Markus;Sakai,Ko;Fukai,Tomoki
PLOS ONE   8(12)    Dec 2013   [Refereed]
Sakai,Ko
Lecture Notes in Computer Science   8228 291-300   Nov 2013   [Refereed]
酒井,宏;Y.Hatori
Lecture notes in computer science   8131 327-334   Sep 2013   [Refereed]
Physiological studies have reported that the intermediate-level visual area represents primitive shape by the selectivity to curvature and its direction. However, it has not been revealed that what coding scheme underlies the construction of the s...
Sparse representation in the construction of curvature selectivity in V4
Hatori,Y.;Mashita,T.;Sakai,K.
PERCEPTION   42(S) 149-149   Aug 2013   [Refereed]
Wagatsuma,Nobuhiko;Oki,Megumi;Sakai,Ko
Frontiers in Psychology   4 1-17   Mar 2013   [Refereed]
We investigated psychophysically whether feature-based attention modulates the perception of figure ground (F-G) segregation and, based on the results, we investigated computationally the neural mechanisms underlying attention modulation. In the p...
Surface representation in early visual cortices for the construction of curvature selectivity in V4
羽鳥,康裕;酒井,宏
IEICE technical report. Neurocomputing   112(480) 73-78   Mar 2013
Accumulated physiological evidence has revealed that V4, an intermediate area of the ventral stream, represents arbitrary object shapes as curvature and its direction. In the present study, we investigated computationally that surface representati...
Symmetry in natural image contour : exploring cortical representation of shape by symmetry
KUREMATSU,Ken;SAKAI,Ko
ITE Technical Report   37(12) 13-16   Feb 2013
Symmetry is a significant factor for deriving the direction of figure. Although symmetry is common among both biological shapes and artificial objects, and known as a Gestalt factor, few studies have quantified its nature and analyzed the function...
Surface-based construction of curvature selectivity from the integration of local orientations
Y.,Hatori and Ko Sakai
Lecture Notes in Computer Science   7663 425-434   Nov 2012   [Refereed]
Structures of Surround Modulation for the Border-Ownership Selectivity of V2 cells
Y.,Nakata and K. Sakai
Lecture Notes in Computer Science   7663 383-392   Nov 2012   [Refereed]
K., Sakai;H., Nishimura;R., Shimizu;K., Kondo
Neural Networks   33 257-274   Sep 2012   [Refereed]
Determination of the figure region in an image is a fundamental step toward surface construction, shape coding, and object representation. Localized, asymmetric surround modulation, reported neurophysiologically in early-to-intermediate-level visu...
Structures of Surround Modulation eliciting Direction of Figure Selectivity : Mathematical Analysis by SVM
NAKATA,Yusuke;SAKAI,Ko
IEICE technical report. Neurocomputing   111(483) 69-74   Mar 2012
The determination of Border-Ownership along contour is a crucial step toward figure-ground segregation. Recent physiological and computational studies have reported that the cells in V2/V4 are selective to BO, and that surround modulation underlie...
Promotion of Border-Ownership perception by multiple Gestalt factor
MATSUOKA,Shohei;SAKAI,Ko
ITE Technical Report   36(13) 13-16   Feb 2012
Gestalt factors are known as cues for the perception of the direction of figure. A previous study has suggested that the promotion of the direction of figure depends on "convexity" and "closure" among Gestalt factors in local contours of natural i...
Sakai, Ko;Ogiya, Mitsuharu;Hirai, Yuzo
JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION   28(7) 1445-1452   Jul 2011   [Refereed]
Sparse Coding for the Representation of Shape in Cortical Area V4 : A Computational Study
MASHITA,Tatsuroh;SAKAI,Ko
ITE Technical Report   35(16) 97-100   Mar 2011
We examined the essence of the receptive-filed properties of V4 neurons from the view point of information, specifically whether the coding of V4 neurons is in a form of sparse representation. The component analyses with the constraint of sparsene...
Medial Axis for 3D Shape Representation
W. Qiu and K.Sakai;
Lecture Notes in Computer Science   7062 79-87   Jan 2011   [Refereed]
Medial Axis for the Cortical Representation of 3D Shape
QIU,Wei;SAKAI,Ko
IEICE technical report. Neurocomputing   110(388) 81-86   Jan 2011
The representation of shape in visual cortex is a fundamental problem in vision science. Physiological studies on monkeys have suggested the representation by two-dimensional medial axis (2D MA) in the primary visual cortex (V1). Binocular fusion ...
研究最前線---ニューロコンピューティング
花沢明俊;酒井, 宏;三浦健一郎
電子情報通信学会,情報・システムソサエティ誌   15(4) 16-17   Jan 2011
Medial Axis for the Cortical Representation of 3D Shape
QIU,Wei;SAKAI,Ko
IEICE technical report. Nonlinear problems   110(387) 81-86   Jan 2011
The representation of shape in visual cortex is a fundamental problem in vision science. Physiological studies on monkeys have suggested the representation by two-dimensional medial axis (2D MA) in the primary visual cortex (V1). Binocular fusion ...
Gestalt factors derived from border-ownership selective cells
KONDO,Keiichi;SAKAI,Ko
IEICE technical report. Neurocomputing   110(149) 57-61   Jul 2010
Border-Ownership (BO) is known as an early mechanism for figure/ground segregation in human vision. BO-selective cells have been reported in the visual cortex of monkeys. A computational model of BO-selective cells has been proposed, which showed ...
Representation of Shape by Medial Axis in Cerebral Cortex
Quiros-Ramirez,Maria Alejandra;Hatori,Yasuhiro;Sakai,Ko
ITE Technical Report   34(11) 1-4   Mar 2010
Daily life presents us with a wide variety of shapes that we recognize immediately even if the figures are occluded partially. Physiological studies with macaques suggested the presence of Medial Axis (MA) transform for shape coding in the cortica...
3ZN-7 Modulation of Shape perception by Contour Synchronization
Matsumoto,Ryuji;Sakai,Ko
全国大会講演論文集   72(5) -153   Mar 2010
3ZN-5 Feature-based Attention Modulates Perception of Figure Direction
Oki,Megumi;Wagatsuma,Nobuhiko;Sakai,Ko
全国大会講演論文集   72(5) -149   Mar 2010
Perceptual Modulation of the Direction of Figure Based on the Feature-based Attention
WAGATSUMA,Nobuhiko;OKI,Megumi;SAKAI,Ko
IEICE technical report. Neurocomputing   109(461) 379-383   Mar 2010
Attentional modulation in early vision might affect the determination of border-ownership (BO) that indicates the direction of figure with respect to the border. The purpose of my study is to investigate the role of feature-based attention applied...
3ZN-2 Quantitative analysis of impression evoked by object arrangement.
Yamasaki,Sho;Sakai,Ko
全国大会講演論文集   72(5) -143   Mar 2010
3ZN-6 Cortical Origin of Gestalt Factors-Quantitative Evaluation of Surround Modulation
Kondo,Keiichi;Sakai,Ko
全国大会講演論文集   72(5) -151   Mar 2010
Roles of Early Vision for the Dynamics of Border-Ownership Selective Neurons.
N., Wagatsuma;K., Sakai
Lecture Notes in Computer Science   6443 99-106   Jan 2010   [Refereed]
Feature-based attention induced by motion direction modulates perception of figure direction
OKI,Megumi;WAGATSUMA,Nobuhiko;SAKAI,Ko
IEICE technical report. Neurocomputing   109(333) 1-6   Dec 2009
Figure-ground segregation plays a crucial role in the process of object recognition. The segregation is modulated by spatial attention as well known in ambiguous figures. We investigated whether feature-based attention modulates the perception of ...
Effects of synchronous representation of contours on shape perception
MITSUOKA,Aya;HATORI,Yasuhiro;SAKAI,Ko
ITE Technical Report   33(17) 41-44   Mar 2009
Medial-axis representation of object shape in V1 and the synchronous firing of neurons attract attention as mechanisms of shape perception. Although physiological studies on synchronization have been advanced, the direct evidence of synchronizatio...
Statistical analysis of information expression in V1 receipt field with sparseness constraint
HIROSE,Yoshitaka;SAKAI,Ko
ITE Technical Report   33(17) 33-36   Mar 2009
We discuss the information representation in V1 neurons including their surround modulation, with specific interests on sparseness in their coding. We compared statistical indices, kurtosis and KL divergence, between the surround-modulation model ...
The Effect of Feature-based Attention on Perception of Border-ownership : Psychophysical Experiments with Attention to Motion Direction
OKI,Megumi;WAGATSUMA,Nobuhiko;SAKAI,Ko
ITE Technical Report   33(17) 37-40   Mar 2009
Figure-ground segregation and the determination of the figure direction are the necessary process for the object recognition. We investigated the effect of the feature-based attention for the perception of figure direction through the psychophysic...
Attention in Early Vision for the Determination of Border-Ownership
WAGATSUMA,Nobuhiko;SHIMIZU,Ryohei;SAKAI,Ko
IEICE technical report. Neurocomputing   108(480) 165-169   Mar 2009
Attentional modulation in early vision might affect the determination of border-ownership (BO) that indicates the direction of figure with respect to the border. The purpose of my study is to investigate the role of spatial attention applied to ea...
Medial-Axis representation of shape from onset synchronization
HATORI,Yasuhiro;SAKAI,Ko
IEICE technical report. Neurocomputing   108(480) 153-157   Mar 2009
Shape encoding plays the most important role in the realization of robust shape cognition. Recent physiological studies with Macaque suggested that object shape is encoded by medial-axis in primary visual cortex (V1). We studied what mechanisms re...
Shape-from-highlight with a viewpoint light-source
MURAKAMI,Yukako;SAKAI,Ko
ITE Technical Report   33(17) 77-80   Mar 2009
We studied psychophysically shape-from-highlight with viewpoint light-source. Specifically, we examined the accuracy and the confidence of depth perception in a viewpoint light-source and other light-source conditions. The result showed highlight ...
Detection of Gestalt Factors in Border Ownership Selectivity Based On Surround Modulation
AONO,Kensuke;SHIMIZU,Ryohei;SAKAI,Ko
IEICE technical report. Neurocomputing   108(480) 171-175   Mar 2009
Border-Ownership (BO) selective cell has been reported in early- to intermediate- level visual cortex. A Computational study has suggested that surround modulation underlies this BO selectivity. In a previous study, the model based on surround mod...
Robust detection of medial-axis by onset synchronization of border-ownership selective cells and shape reconstruction from its medial-axis.
Y., Hatori;K., Sakai
Lecture Note in Computer Science (ICONIP 2008)   5506 301-309   Jan 2009   [Refereed]
There is little understanding on representation and reconstruction of object shape in the cortex. Physiological studies with macaque suggested that neurons in VI respond to Medial-Axis (MA). We investigated whether (1) early visual areas could pro...

Books etc

 
感覚・知覚の科学
内川恵二編;+酒井, 宏
朝倉書店   Oct 2008   
面知覚の基礎としての境界所有の皮質メカニズム
酒井, 宏 (Part:Supervisor)
日本神経回路学会誌   Jan 2007   
ヒューマンインフォメーション
塩入, 諭;酒井, 宏;井上哲理;小峯一晃;新井啓之 (Part:Supervisor)
映像情報メディア学会誌   Aug 2006   
ブレインサイエンスレビュー2007
伊藤正男・川合述吏編;+酒井, 宏
クバプロ(株)   Jan 2006   
ヒューマンインフォメーション
塩入諭;酒井, 宏;井上哲理;小峰一晃;新井啓之 (Part:Supervisor)
映像情報メディア学会誌   Aug 2004   

Conference Activities & Talks

 
自然光景における図地分離の局所的手掛かり
碓氷隼也;酒井, 宏
日本視覚学会 冬季大会   29 Jan 2019   
覚醒感情による色知覚の変調
柴田紀代;酒井, 宏
日本視覚学会 冬季大会   29 Jan 2019   
Receptive field structure of border ownership-selective cells in response to natural images.
酒井,宏
平成30年度電気通信研究所共同プロジェクト研究発表会   21 Feb 2019   
サルV4図地選好性細胞の受容野構造
木村, 耕治;山根, ゆか子;田村, 弘;酒井, 宏
電子情報通信学会ニューロコンピューティング研究会   5 Mar 2019   電子情報通信学会
対称軸への順応---形状とパターンの相互作用
坂田結衣;酒井, 宏
日本神経回路学会,全国大会   20 Sep 2017   日本神経回路学会

Teaching Experience

 
 

Research Grants & Projects

 
Figure-ground segregation in natural images based on cortical mechanisms for border-ownership determination
Project Year: Sep 2006 - Aug 2007