Functional connectivity MR imaging

Abstract

Brain function arises out of interactions between brain areas. Neuroimaging studies of brain function are, therefore, concerned not only with activity in discrete brain areas but also with the interactions between areas. A variety of approaches have been developed to study these interactions. The simplest of these is to examine functional connectivity, defined as “temporal correlations between spatially remote neurophysio-logical events” [1, 2]. Because functional connectivity is defined as a correlation, it does not imply causal effects. The term effective connectivity is used to describe the “influence that one neural system exerts over another.” [1] This chapter is focused on the methods and applications of functional connectivity analyses. The reader is referred elsewhere for information about current approaches for inferring effective connectivity [3-6].