Repository of MATLAB scripts that I wrote as a graduate student (2011-2013) to perform multivoxel pattern analysis (MVPA) of functional magnetic resonance imaging (fMRI) data. MVPA is a novel data mining method in fMRI research to analyze distributed patterns of brain activity, which the human brain uses to represent information (Mahmoudi, Takerkart, Regragui, Boussaoud, & Brovelli, 2012). Variations of some of the scripts in this repository were used for two scientific publications (Contreras, Banaji, & Mitchell, 2013; Contreras, Schirmer, Banaji, & Mitchell, 2013).
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searchlight.m uses parameter estimates from SPM8 images to perform two types of MVPA: Whole-brain searchlights (Kriegeskorte, Goebel, & Bandettini, 2006) and region-of-interest (ROI) analyses. It ouputs the resulting statistics as .mat files and brain images. It serves as a wrapper to the following four scripts.
- searchlightSEL.m selects which MVPA to execute: individual- and/or group-level searchlight, or ROI analysis
- searchlightONE.m computes individual-level searchlights
- searchlightRFX.m uses searchlight results produced by searchlightONE.m to perform a group-level analysis
- searchlightROI.m executes an ROI analysis given a brain mask denoting one or more ROIs
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r2z.m applies a Fisher transformation to transform correlation coefficients to z-statistics.
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temporalSNR.m computes temporal signal-to-noise ratio, number of experimental timepoints, or effect size in an fMRI experiment given two of these variables and a p-value (Murphy, Bodzurka, & Bandettini, 2007).