A test for a conjunction

✍ Scribed by K.J. Worsley; K.J. Friston

• Book ID: 104303235
• Publisher: Elsevier Science
• Year: 2000
• Tongue: English
• Weight: 198 KB
• Volume: 47
• Category: Article
• ISSN: 0167-7152
• DOI: 10.1016/s0167-7152(99)00149-2

✦ Synopsis

A conjunction is deÿned in the brain mapping literature as the occurrence of the same event at the same location in two or more independent 3D brain images. The images are smooth isotropic 3D random ÿelds of test statistics, and the event occurs when the image exceeds a ÿxed high threshold. We give a simple approximation to the probability of a conjunction occurring anywhere in a ÿxed region, so that we can test for a local increase in the mean of the images at the same unknown location in all images, a generalization of the split-t test. This is the corollary to a more general result on the expected Minkowski functionals of the set of points where a conjunction occurs.