Computational protocol: Mapping the “What” and “Where” Visual Cortices and Their Atrophy in Alzheimer's Disease: Combined Activation Likelihood Estimation with Voxel-Based Morphometry

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Protocol publication

[…] The 93 studies fitting within the established criteria were first divided into two major categories of “what” and “where” visions. These included studies of face, object, alphabetic word/letter, logographic word/symbol, scene, body, motion, and spatial visions, respectively. These studies were further classified into eight basic visual categories of motion, space, object, face, alphabetic word/letter (word for short), logographic word/symbol, scene, and body visions (Supplementary Table ). To ensure the power of the results, visual functions with less than 10 experiments (i.e., body, scene and logographic word visions) were not used to establish an independent category. Consequently, five categories remained.To identify the specific brain regions responsible for particular visual functions, we subsequently conducted a contrast analysis of each pair from the task categories of face-word, face-object, object-word and “what”–“where” vision. Contrast analyses between motion and spatial vision were not performed due to the large difference in the number of included studies between these two categories, which might have impacted the power of the statistical results.The Ginger ALE software program, version 2.0 (available at http://www.brainmap.org/ale) with revised ALE algorithm implemented in was used. ALE is a coordinate-based meta-analysis tool that treats significant foci reported in neuroimaging studies not as single points but as spatial probability distributions centered at the given coordinates. ALE maps are then produced by computing the union of activation probabilities for each voxel (Eickhoff et al., ; Turkeltaub et al., ). First, coordinates of the original studies reported in the Talairach brain map were transformed into the MNI space using the Lancaster transform (Lancaster et al., ). The foci from each individual study were smoothed by a full width half maximum (FWHM) value scaled by the study's sample size to model the uncertainty in the spatial location of the activations (Eickhoff et al., ). An analytical method was used to determine the null distribution of the ALE statistic, and correction for multiple comparisons was then applied using the false discovery rate (FDR pN; Laird et al., ), with p < 0.01. A minimum cluster volume of 200 mm3 was applied. The statistical level for contrast analysis was also set at p < 0.01 (FDR pN corrected) with a minimum volume ≥ 200 mm3. The generated ALE maps were overlaid on a Colin_tlrc_2 × 2 × 2 template using the MANGO software program for visualization (http://rii.uthscsa.edu/mango/). […]

Pipeline specifications

Software tools BrainMap, Mango
Application Neuroimaging analysis
Organisms Homo sapiens
Diseases Alzheimer Disease