title: Searchlight analysis: promise, pitfalls, and potential.
abstract: Multivariate pattern analysis (MVPA) is an increasingly popular approach for characterizing the information present in neural activity as measured by fMRI. For neuroimaging researchers, the searchlight technique serves as the most intuitively appealing means of implementing MVPA with fMRI data. However, searchlight approaches carry with them a number of special concerns and limitations that can lead to serious interpretation errors in practice, such as misidentifying a cluster as informative, or failing to detect truly informative voxels. Here we describe how such distorted results can occur, using both schematic illustrations and examples from actual fMRI datasets. We recommend that confirmatory and sensitivity tests, such as the ones prescribed here, should be considered a necessary stage of searchlight analysis interpretation, and that their adoption will allow the full potential of searchlight analysis to be realized.
authors.affiliation: Cognitive Control & Psychopathology Lab, Washington University in St. Louis, 1 Brookings Drive, St. Louis, MO 63130, USA. jetzel@artsci.wustl.edu
authors.forename: Joset A
authors.initials: JA
authors.lastname: Etzel
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Zacks
authors.forename: Todd S
authors.initials: TS
authors.lastname: Braver
mesh_terms: D001921:Brain / Q000502:physiology*; D001931:Brain Mapping / Q000379:methods*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging; D015999:Multivariate Analysis; D060388:Support Vector Machine
references.citation: Nat Neurosci. 2005 May;8(5):686-91
references.pmid: 15852013
references.citation: Nat Rev Cancer. 2008 Jan;8(1):37-49
references.pmid: 18097463
references.citation: Proc Natl Acad Sci U S A. 2011 Jun 14;108(24):9998-10003
references.pmid: 21628569
references.citation: Neuroimage. 2006 Dec;33(4):1055-65
references.pmid: 17010645
references.citation: Science. 2001 Sep 28;293(5539):2425-30
references.pmid: 11577229
references.citation: Neurosci Bull. 2012 Aug;28(4):399-408
references.pmid: 22833038
references.citation: Neuropsychologia. 2012 Mar;50(4):544-52
references.pmid: 22100534
references.citation: Nat Neurosci. 2009 May;12(5):535-40
references.pmid: 19396166
references.citation: Med Image Comput Comput Assist Interv. 2012;15(Pt 1):723-30
references.pmid: 23285616
references.citation: J Neurosci. 2009 Feb 4;29(5):1565-72
references.pmid: 19193903
references.citation: Neuroimage. 2012 Aug 15;62(2):852-5
references.pmid: 22425670
references.citation: IEEE Trans Med Imaging. 2011 Aug;30(8):1441-54
references.pmid: 21324774
references.citation: Curr Biol. 2007 Feb 20;17(4):323-8
references.pmid: 17291759
references.citation: Ann N Y Acad Sci. 2009 Mar;1156:260-93
references.pmid: 19338512
references.citation: Curr Biol. 2006 Jun 6;16(11):1096-102
references.pmid: 16753563
references.citation: J Cogn Neurosci. 2011 Oct;23(10):2636-49
references.pmid: 21268671
references.citation: Annu Rev Psychol. 2012;63:483-509
references.pmid: 21943172
references.citation: Med Image Anal. 2011 Oct;15(5):729-37
references.pmid: 21752695
references.citation: Proc Natl Acad Sci U S A. 2006 Mar 7;103(10):3863-8
references.pmid: 16537458
references.citation: Nature. 2008 Mar 20;452(7185):352-5
references.pmid: 18322462
references.citation: Neuroimage. 2011 May 15;56(2):582-92
references.pmid: 20656043
references.citation: Science. 2008 May 30;320(5880):1191-5
references.pmid: 18511683
references.citation: Neuroimage. 2011 May 15;56(2):476-96
references.pmid: 20488249
references.citation: Nat Neurosci. 2005 May;8(5):679-85
references.pmid: 15852014
references.citation: Science. 2009 Jun 19;324(5934):1583-5
references.pmid: 19423779
references.citation: Neuroimage. 2013 Jan 15;65:69-82
references.pmid: 23041526
references.citation: Neuroimage. 2007 Dec;38(4):649-62
references.pmid: 17804260
references.citation: Int Workshop Pattern Recognit Neuroimaging. 2012 Jul 2;2012:33-36
references.pmid: 25984554
references.citation: Neuroimage. 2010 Feb 1;49(3):1965-76
references.pmid: 19800408
references.citation: Neuroimage. 2010 Feb 1;49(3):1943-8
references.pmid: 19285144
references.citation: Perspect Psychol Sci. 2009 May;4(3):294-8
references.pmid: 26158966
references.citation: Proc Natl Acad Sci U S A. 2012 Apr 3;109(14):5487-92
references.pmid: 22431587
references.citation: Trends Cogn Sci. 2006 Sep;10(9):424-30
references.pmid: 16899397
references.citation: Neuroimage. 2011 May 15;56(2):508-16
references.pmid: 20674749
references.citation: J Neurophysiol. 2010 Aug;104(2):1077-89
references.pmid: 20538772
references.citation: Cereb Cortex. 2013 Jun;23(6):1362-77
references.pmid: 22610393
references.citation: J Cogn Neurosci. 2003 Jul 1;15(5):704-17
references.pmid: 12965044
references.citation: Neuroimage. 2007 Dec;38(4):666-8
references.pmid: 17976583
references.citation: Neuroimage. 2011 May 15;56(2):593-600
references.pmid: 20621701
references.citation: Curr Biol. 2009 Oct 13;19(19):1608-15
references.pmid: 19781939