Useful Papers - Connectivity
Summary: An excellent overview of the state of connectivity analyses today, with a survey of current methods, pitfalls, and open questions. Many terms are clearly defined. The overview looks not only at human neuroimaging techniques, but at a variety of anatomical techniques from various species.
Summary: A sort of minority opinion, to go with Lee et. al (above). Essentially a deeper primer on the pitfalls of studying connectivity, Horwitz raises questions about just how clear any of the term used in the field are at their core. In particular, he highlights the point that different neuroimaging techniques probably study very different types of connectivity, and their results may not be directly comparable.
Summary: The first introduction to the DCM concept, and necessary reading for the current state of connectivity research. The DCM framework essentially expands on the classic general linear model, adding in bilinear terms that attempt to model resting connectivity between regions and how experimental manipulations change that connectivity. Friston demonstrates how DCM encompasses a variety of other techniques (SEM, etc.) and explicitly includes the temporal dimension in assessing connectivity.
Summary: A really interesting example of DCM use in a real-world setting. Authors used the dataset from another study, provided by the fMRI Data Center, and applied DCM to examine the connection between secondary visual areas and parietal regions. They discovered that category effects - differences in responses between chairs, faces, and houses - in occipital and temporal cortex are mediated by very early visual effects - not just top-down effects.
Summary: A recent example of the SEM approach. Kondo et. al used SEM to model the connection between ACC and PFC in high-reading-span and low-reading-span groups, discovering a closer connection in the former than the latter. Some discussion of how SEM is carried out, as a guide for those wishing to try the method.
Summary: Yet another approach to measuring connectivity, this time from the BrainVoyager group and attempting to impose some concept of directionality on the connectivity analyses. The concept of Granger causality - imported from economics - is described from a neuroimaging point of view. The VAR framework (a multivariate technique) is described and used to analyze a visuomotor mapping study.