Effective paradigm design

Advances in functional magnetic resonance imaging (fMRI) are affording numerous new ways to design and analyse brain-imaging studies. A major driving force for these advances has been the widespread use of MRI scanners capable of ultra-fast imaging. This chapter aims to review key aspects of magnetic resonance imaging (MRI) technology and of the underlying physiology that constrains paradigm design for functional brain imaging. It reviews issues related to the design of event-related experimental paradigms and discusses how event related procedures have extended the range of questions that can be dealt. The chapter introduces the concept of mixed 'blocked and event-related' procedures. The development of such 'mixed' procedures widens the spectrum of task designs and analytical techniques that can be used. The chapter also extends the range of questions that can be addressed with fMRI, and presents a brief review of the underlying characteristics of the haemodynamic response, to provide a framework for discussion of event-related methods and their derivatives.