AUTHOR=Munilla Jorge , Ortiz Andrés , Górriz Juan M. , Ramírez Javier ,  the Alzheimer's Disease Neuroimaging Initiative , Weiner Michael W. , Aisen Paul , Weiner Michael , Aisen Paul , Petersen Ronald , Jack Clifford R. , Jagust William , Trojanowki John Q. , Toga Arthur W. , Beckett Laurel , Green Robert C. , Saykin Andrew J. , Morris John , Shaw Leslie M. , Khachaturian Zaven , Sorensen Greg , Carrillo Maria , Kuller Lew , Raichle Marc , Paul Steven , Davies Peter , Fillit Howard , Hefti Franz , Holtzman David , Mesulam M. Marcel , Potter William , Snyder Peter , Schwartz Adam , Green Robert C. , Montine Tom , Petersen Ronald , Aisen Paul , Thomas Ronald G. , Donohue Michael , Walter Sarah , Gessert Devon , Sather Tamie , Jiminez Gus , Balasubramanian Archana B. , Mason Jennifer , Sim Iris , Beckett Laurel , Harvey Danielle , Donohue Michael , Jack Clifford R. , Bernstein Matthew , Fox Nick , Thompson Paul , Schuff Norbert , DeCArli Charles , Borowski Bret , Gunter Jeff , Senjem Matt , Vemuri Prashanthi , Jones David , Kantarci Kejal , Ward Chad , Jagust William , Koeppe Robert A. , Foster Norm , Reiman Eric M. , Chen Kewei , Mathis Chet , Landau Susan , Morris John C. , Cairns Nigel J. , Franklin Erin , Taylor-Reinwald Lisa , Shaw Leslie M. , Trojanowki John Q. , Lee Virginia , Korecka Magdalena , Figurski Michal , Toga Arthur W. , Crawford Karen , Neu Scott , Saykin Andrew J. , Foroud Tatiana M. , Potkin Steven , Shen Li , Faber Kelley , Kim Sungeun , Nho Kwangsik , Weiner Michael W. , Thal Lean , Khachaturian Zaven , Thal Leon , Buckholtz Neil , Weiner Michael W. , Snyder Peter J. , Potter William , Paul Steven , Albert Marilyn , Frank Richard , Khachaturian Zaven , Hsiao John , Kaye Jeffrey , Quinn Joseph , Silbert Lisa , Lind Betty , Carter Raina , Dolen Sara , Schneider Lon S. , Pawluczyk Sonia , Becerra Mauricio , Teodoro Liberty , Spann Bryan M. , Brewer James , Vanderswag Helen , Fleisher Adam , Heidebrink Judith L. , Lord Joanne L. , Petersen Ronald , Mason Sara S. , Albers Colleen S. , Knopman David , Johnson Kris , Doody Rachelle S. , Villanueva-Meyer Javier , Pavlik Valory , Shibley Victoria , Chowdhury Munir , Rountree Susan , Dang Mimi , Stern Yaakov , Honig Lawrence S. , Bell Karen L. , Ances Beau , Morris John C. , Carroll Maria , Creech Mary L. , Franklin Erin , Mintun Mark A. , Schneider Stacy , Oliver Angela , Marson Daniel , Geldmacher David , Natelson Love Marissa , Griffith Randall , Clark David , Brockington John , Roberson Erik , Grossman Hillel , Mitsis Effie , Shah Raj C. , deToledo-Morrell Leyla , Duara Ranjan , Greig-Custo Maria T. , Barker Warren , Albert Marilyn , Onyike Chiadi , D'Agostino Daniel , Kielb Stephanie , Sadowski Martin , Sheikh Mohammed O. , Anaztasia Ulysse , Mrunalini Gaikwad , Doraiswamy P. Murali , Petrella Jeffrey R. , Borges-Neto Salvador , Wong Terence Z. , Coleman Edward , Arnold Steven E. , Karlawish Jason H. , Wolk David A. , Clark Christopher M. , Smith Charles D. , Jicha Greg , Hardy Peter , Sinha Partha , Oates Elizabeth , Conrad Gary , Lopez Oscar L. , Oakley MaryAnn , Simpson Donna M. , Porsteinsson Anton P. , Goldstein Bonnie S. , Martin Kim , Makino Kelly M. , Ismail M. Saleem , Brand Connie , Potkin Steven G. , Preda Adrian , Nguyen Dana , Womack Kyle , Mathews Dana , Quiceno Mary , Levey Allan I. , Lah James J. , Cellar Janet S. , Burns Jeffrey M. , Swerdlow Russell H. , Brooks William M. , Apostolova Liana , Tingus Kathleen , Woo Ellen , Silverman Daniel H.S. , Lu Po H. , Bartzokis George , Graff-Radford Neill R , Parfitt Francine , Poki-Walker Kim , Farlow Martin R. , Hake Ann Marie , Matthews Brandy R. , Brosch Jared R. , Herring Scott , van Dyck Christopher H. , Carson Richard E. , MacAvoy Martha G. , Varma Pradeep , Chertkow Howard , Bergman Howard , Hosein Chris , Black Sandra , Stefanovic Bojana , Caldwell Curtis , Hsiung Ging-Yuek Robin , Mudge Benita , Sossi Vesna , Feldman Howard , Assaly Michele , Finger Elizabeth , Pasternack Stephen , Rachisky Irina , Trost Dick , Kertesz Andrew , Bernick Charles , Munic Donna , Mesulam Marek-Marsel , Rogalski Emily , Lipowski Kristine , Weintraub Sandra , Bonakdarpour Borna , Kerwin Diana , Wu Chuang-Kuo , Johnson Nancy , Sadowsky Carl , Villena Teresa , Turner Raymond Scott , Johnson Kathleen , Reynolds Brigid , Sperling Reisa A. , Johnson Keith A. , Marshall Gad , Yesavage Jerome , Taylor Joy L. , Lane Barton , Rosen Allyson , Tinklenberg Jared , Sabbagh Marwan N. , Belden Christine M. , Jacobson Sandra A. , Sirrel Sherye A. , Kowall Neil , Killiany Ronald , Budson Andrew E. , Norbash Alexander , Johnson Patricia Lynn , Obisesan Thomas O. , Wolday Saba , Allard Joanne , Lerner Alan , Ogrocki Paula , Tatsuoka Curtis , Fatica Parianne , Fletcher Evan , Maillard Pauline , Olichney John , DeCarli Charles , Carmichael Owen , Kittur Smita , Borrie Michael , Lee T-Y , Bartha Rob , Johnson Sterling , Asthana Sanjay , Carlsson Cynthia M. , Potkin Steven G. , Preda Adrian , Nguyen Dana , Tariot Pierre , Burke Anna , Milliken Ann Marie , Trncic Nadira , Fleisher Adam , Reeder Stephanie , Bates Vernice , Capote Horacio , Rainka Michelle , Scharre Douglas W. , Kataki Maria , Kelley Brendan , Zimmerman Earl A. , Celmins Dzintra , Brown Alice D. , Pearlson Godfrey D. , Blank Karen , Anderson Karen , Flashman Laura A. , Seltzer Marc , Hynes Mary L. , Santulli Robert B. , Sink Kaycee M. , Leslie Gordineer , Williamson Jeff D. , Garg Pradeep , Watkins Franklin , Ott Brian R. , Tremont Geoffrey , Daiello Lori A. , Salloway Stephen , Malloy Paul , Correia Stephen , Rosen Howard J. , Miller Bruce L. , Perry David , Mintzer Jacobo , Spicer Kenneth , Bachman David , Finger Elizabeth , Pasternak Stephen , Rachinsky Irina , Rogers John , Kertesz Andrew , Drost Dick , Pomara Nunzio , Hernando Raymundo , Sarrael Antero , Schultz Susan K. , Smith Karen Ekstam , Koleva Hristina , Nam Ki Won , Shim Hyungsub , Relkin Norman , Chiang Gloria , Lin Michael , Ravdin Lisa , Smith Amanda , Raj Balebail Ashok , Fargher Kristin , Weiner Michael W. , Aisen Paul , Weiner Michael , Aisen Paul , Petersen Ronald , Green Robert C. , Harvey Danielle , Jack Clifford R. , Jagust William , Morris John C. , Saykin Andrew J. , Shaw Leslie M. , Toga Arthur W. , Trojanowki John Q. , Neylan Thomas , Grafman Jordan , Green Robert C. , Montine Tom , Weiner Michael , Petersen Ronald , Aisen Paul , Thomas Ronald G. , Donohue Michael , Devon Gessert , Sather Tamie , Melissa Davis , Morrison Rosemary , Jiminez Gus , Neylan Thomas , Jacqueline Hayes , Shannon Finley , Harvey Danielle , Donohue Michael , Jack Clifford R. , Bernstein Matthew , Borowski Bret , Gunter Jeff , Senjem Matt , Kejal Kantarci , Chad Ward , Jagust William , Koeppe Robert A. , Foster Norm , Reiman Eric M. , Chen Kewei , Landau Susan , Morris John C. , Cairns Nigel J. , Householder Erin , Shaw Leslie M. , Trojanowki John Q. , Lee Virginia , Korecka Magdalena , Figurski Michal , Toga Arthur W. , Karen Crawford , Scott Neu , Saykin Andrew J. , Foroud Tatiana M. , Potkin Steven , Shen Li , Faber Kelley , Kim Sungeun , Nho Kwangsik , Weiner Michael W. , Karl Friedl , Schneider Lon S. , Pawluczyk Sonia , Mauricio Becerra , Brewer James , Vanderswag Helen , Stern Yaakov , Honig Lawrence S. , Bell Karen L. , Fleischman Debra , Arfanakis Konstantinos , Shah Raj C. , Duara Ranjan , Varon Daniel , Greig Maria T , Doraiswamy P. Murali , Petrella Jeffrey R. , James Olga , Porsteinsson Anton P. , Goldstein Bonnie , Martin Kimberly S. , Potkin Steven G. , Preda Adrian , Nguyen Dana , Mintzer Jacobo , Massoglia Dino , Brawman-Mintzer Olga , Sadowsky Carl , Martinez Walter , Villena Teresa , Jagust William , Landau Susan , Rosen Howard , Perry David , Turner Raymond Scott , Behan Kelly , Reynolds Brigid , Sperling Reisa A. , Johnson Keith A. , Marshall Gad , Sabbagh Marwan N. , Jacobson Sandra A. , Sirrel Sherye A. , Obisesan Thomas O. , Wolday Saba , Allard Joanne , Johnson Sterling C. , Fruehling J. Jay , Harding Sandra , Peskind Elaine R. , Petrie Eric C. , Li Gail , Yesavage Jerome A. , Taylor Joy L. , Furst Ansgar J. , Chao Steven , Relkin Norman , Chiang Gloria , Ravdin Lisa , Ravdin Lisa 

TITLE=Construction and Analysis of Weighted Brain Networks from SICE for the Study of Alzheimer's Disease

JOURNAL=Frontiers in Neuroinformatics

VOLUME=11

YEAR=2017

URL=https://www.frontiersin.org/journals/neuroinformatics/articles/10.3389/fninf.2017.00019

DOI=10.3389/fninf.2017.00019

ISSN=1662-5196

ABSTRACT=<p>Alzheimer's Disease (AD) is the most common neurodegenerative disease in elderly people, and current drugs, unfortunately, do not represent yet a cure but only slow down its progression. This is explained, at least in part, because the understanding of the neurodegenerative process is still incomplete, being sometimes mistaken, particularly at the first steps of the illness, with the natural aging process. A better identification of how the functional activity deteriorates is thus crucial to develop new and more effective treatments. Sparse inverse covariance estimates (SICE) have been recently employed for deriving functional connectivity patterns from Positron Emission Tomography (PET) of brains affected by Alzheimer's Disease. SICE, unlike the traditional covariance methods, allows to analyze the interdependencies between brain regions factoring out the influence of others. To analyze the effects of the illness, connectivity patterns of brains affected by AD are compared with those obtained for control groups. These comparisons are, however, carried out for binary (undirected and unweighted) adjacency matrices with the same number of arcs. Additionally, the effect of the number of subjects employed or the validity of the regularization parameter used to compute the SICE have been not hitherto analyzed. In this paper, we delve into the construction of connectivity patterns from PET using SICE. In particular, we describe the effect that the number of subjects employed has on the results and identify, based on the reconstruction error of linear regression systems, a range of valid values for the regularization parameter. The amount of arcs is also proved as a discriminant value, and we show that it is possible to pass from unweighted (binary) to weighted adjacency matrices, where the weight of a connection corresponding to the existence of a relationship between two brain areas can be correlated to the persistence of this relationship when computed for different values of the regularization parameter and sets of subjects. Finally, network measures are computed for the connectivity patterns confirming that SICE may be particularly apt for assessing the efficiency of drugs, since it produces reliable brain connectivity models with small sample sizes, and that connectivity patterns affected by AD seem much less segregated, reducing the small-worldness.</p>